diff --git a/plugins/YammerImport/README b/plugins/YammerImport/README
index 975faa2132..db16744dce 100644
--- a/plugins/YammerImport/README
+++ b/plugins/YammerImport/README
@@ -139,8 +139,6 @@ File type and size limitations on attachments will be applied, so beware some
 attachments may not make it through.
 
 
-
-
 Code structure
 ==============
 
@@ -179,4 +177,3 @@ Yammer_notice_stub: data object for temporary storage of fetched Yammer messages
 Yammer_user,
 Yammer_group,
 Yammer_notice: data objects mapping original Yammer item IDs to their local copies.
-
diff --git a/plugins/YammerImport/actions/yammeradminpanel.php b/plugins/YammerImport/actions/yammeradminpanel.php
index 4714154290..493762e2cd 100644
--- a/plugins/YammerImport/actions/yammeradminpanel.php
+++ b/plugins/YammerImport/actions/yammeradminpanel.php
@@ -42,6 +42,7 @@ class YammeradminpanelAction extends AdminPanelAction
      */
     function title()
     {
+        // TRANS: Page title for Yammer import administration panel.
         return _m('Yammer Import');
     }
 
@@ -52,6 +53,7 @@ class YammeradminpanelAction extends AdminPanelAction
      */
     function getInstructions()
     {
+        // TRANS: Instructions for Yammer import administration panel.
         return _m('This Yammer import tool is still undergoing testing, ' .
                   'and is incomplete in some areas. ' .
                 'Currently user subscriptions and group memberships are not ' .
@@ -111,7 +113,8 @@ class YammeradminpanelAction extends AdminPanelAction
             } else if ($this->subaction == 'progress') {
                 $form = $this->statusForm();
             } else {
-                throw new ClientException('Invalid POST');
+                // TRANS: Client exception thrown when encountering an unhandled sub action.
+                throw new ClientException(_m('Invalid POST'));
             }
             return $this->showAjaxForm($form);
         }
@@ -132,6 +135,7 @@ class YammeradminpanelAction extends AdminPanelAction
     {
         $this->startHTML('text/xml;charset=utf-8');
         $this->elementStart('head');
+        // TRANS: Page title for Yammer import administration panel.
         $this->element('title', null, _m('Yammer import'));
         $this->elementEnd('head');
         $this->elementStart('body');
diff --git a/plugins/YammerImport/actions/yammerauth.php b/plugins/YammerImport/actions/yammerauth.php
index d0d4b40c71..d25be91440 100644
--- a/plugins/YammerImport/actions/yammerauth.php
+++ b/plugins/YammerImport/actions/yammerauth.php
@@ -33,7 +33,6 @@ if (!defined('STATUSNET')) {
 
 class YammerauthAction extends AdminPanelAction
 {
-
     /**
      * Show the Yammer admin panel form
      *
@@ -42,7 +41,7 @@ class YammerauthAction extends AdminPanelAction
     function prepare($args)
     {
         parent::prepare($args);
-        
+
         $this->verify_token = $this->trim('verify_token');
     }
 
@@ -55,7 +54,6 @@ class YammerauthAction extends AdminPanelAction
      *
      * @return void
      */
-
     function handle($args)
     {
         if ($this->verify_token) {
@@ -68,6 +66,7 @@ class YammerauthAction extends AdminPanelAction
 
         $this->startHTML('text/xml;charset=utf-8');
         $this->elementStart('head');
+        // TRANS: Page title for Yammer administration panel.
         $this->element('title', null, _m('Connect to Yammer'));
         $this->elementEnd('head');
         $this->elementStart('body');
@@ -76,4 +75,3 @@ class YammerauthAction extends AdminPanelAction
         $this->elementEnd('html');
     }
 }
-
diff --git a/plugins/YammerImport/classes/Yammer_common.php b/plugins/YammerImport/classes/Yammer_common.php
index 6ec6fc9041..e262623263 100644
--- a/plugins/YammerImport/classes/Yammer_common.php
+++ b/plugins/YammerImport/classes/Yammer_common.php
@@ -40,7 +40,6 @@ if (!defined('STATUSNET')) {
  * - schemaDef (call self::doSchemaDef)
  * - record (call self::doRecord)
  */
-
 class Yammer_common extends Memcached_DataObject
 {
     public $__table = 'yammer_XXXX'; // table name
@@ -50,7 +49,7 @@ class Yammer_common extends Memcached_DataObject
     public $created;                 // datetime
 
     /**
-     * @fixme add a 'references' thing for the foreign key when we support that
+     * @todo FIXME: Add a 'references' thing for the foreign key when we support that
      */
     protected static function doSchemaDef($field)
     {
@@ -87,7 +86,6 @@ class Yammer_common extends Memcached_DataObject
      *
      * @return array list of key field names
      */
-
     function keys()
     {
         return array_keys($this->keyTypes());
@@ -105,7 +103,6 @@ class Yammer_common extends Memcached_DataObject
      *         'K' for primary key: for compound keys, add an entry for each component;
      *         'U' for unique keys: compound keys are not well supported here.
      */
-
     function keyTypes()
     {
         return array('id' => 'K', $this->__field => 'U');
@@ -121,7 +118,6 @@ class Yammer_common extends Memcached_DataObject
      *
      * @return array magic three-false array that stops auto-incrementing.
      */
-
     function sequenceKey()
     {
         return array(false, false, false);
@@ -135,7 +131,6 @@ class Yammer_common extends Memcached_DataObject
      *
      * @return Yammer_common new object for this value
      */
-
     protected static function doRecord($class, $field, $orig_id, $local_id)
     {
         $map = parent::staticGet($class, 'id', $orig_id);
diff --git a/plugins/YammerImport/classes/Yammer_group.php b/plugins/YammerImport/classes/Yammer_group.php
index 4e7a6ebd03..a52b5119d4 100644
--- a/plugins/YammerImport/classes/Yammer_group.php
+++ b/plugins/YammerImport/classes/Yammer_group.php
@@ -48,7 +48,6 @@ class Yammer_group extends Yammer_common
      * @return Yammer_group object found, or null for no hits
      *
      */
-
     function staticGet($k, $v=null)
     {
         return Memcached_DataObject::staticGet('Yammer_group', $k, $v);
@@ -57,7 +56,6 @@ class Yammer_group extends Yammer_common
     /**
      * Return schema definition to set this table up in onCheckSchema
      */
-
     static function schemaDef()
     {
         return self::doSchemaDef('group_id');
@@ -71,7 +69,6 @@ class Yammer_group extends Yammer_common
      *
      * @return Yammer_group new object for this value
      */
-
     static function record($orig_id, $group_id)
     {
         return self::doRecord('Yammer_group', 'group_id', $orig_id, $group_id);
diff --git a/plugins/YammerImport/classes/Yammer_notice.php b/plugins/YammerImport/classes/Yammer_notice.php
index 0f63db6303..118266aed0 100644
--- a/plugins/YammerImport/classes/Yammer_notice.php
+++ b/plugins/YammerImport/classes/Yammer_notice.php
@@ -48,7 +48,6 @@ class Yammer_notice extends Yammer_common
      * @return Yammer_notice object found, or null for no hits
      *
      */
-
     function staticGet($k, $v=null)
     {
         return Memcached_DataObject::staticGet('Yammer_notice', $k, $v);
@@ -57,7 +56,6 @@ class Yammer_notice extends Yammer_common
     /**
      * Return schema definition to set this table up in onCheckSchema
      */
-
     static function schemaDef()
     {
         return self::doSchemaDef('notice_id');
@@ -71,7 +69,6 @@ class Yammer_notice extends Yammer_common
      *
      * @return Yammer_notice new object for this value
      */
-
     static function record($orig_id, $notice_id)
     {
         return self::doRecord('Yammer_notice', 'notice_id', $orig_id, $notice_id);
diff --git a/plugins/YammerImport/classes/Yammer_notice_stub.php b/plugins/YammerImport/classes/Yammer_notice_stub.php
index e10300c4c7..6dd78206d2 100644
--- a/plugins/YammerImport/classes/Yammer_notice_stub.php
+++ b/plugins/YammerImport/classes/Yammer_notice_stub.php
@@ -40,7 +40,6 @@ if (!defined('STATUSNET')) {
  * down in reverse chronological order, then go back over them from oldest to
  * newest and actually save them into our notice table.
  */
-
 class Yammer_notice_stub extends Memcached_DataObject
 {
     public $__table = 'yammer_notice_stub'; // table name
@@ -57,9 +56,7 @@ class Yammer_notice_stub extends Memcached_DataObject
      * @param mixed  $v Value to lookup
      *
      * @return Yammer_notice_stub object found, or null for no hits
-     *
      */
-
     function staticGet($k, $v=null)
     {
         return Memcached_DataObject::staticGet('Yammer_notice_stub', $k, $v);
@@ -86,7 +83,6 @@ class Yammer_notice_stub extends Memcached_DataObject
      *
      * @return array array of column definitions
      */
-
     function table()
     {
         return array('id'           => DB_DATAOBJECT_INT + DB_DATAOBJECT_NOTNULL,
@@ -121,7 +117,6 @@ class Yammer_notice_stub extends Memcached_DataObject
      *         'K' for primary key: for compound keys, add an entry for each component;
      *         'U' for unique keys: compound keys are not well supported here.
      */
-
     function keyTypes()
     {
         return array('id' => 'K');
@@ -137,7 +132,6 @@ class Yammer_notice_stub extends Memcached_DataObject
      *
      * @return array magic three-false array that stops auto-incrementing.
      */
-
     function sequenceKey()
     {
         return array(false, false, false);
diff --git a/plugins/YammerImport/classes/Yammer_state.php b/plugins/YammerImport/classes/Yammer_state.php
index 88bd693bfd..548fbbf024 100644
--- a/plugins/YammerImport/classes/Yammer_state.php
+++ b/plugins/YammerImport/classes/Yammer_state.php
@@ -55,9 +55,7 @@ class Yammer_state extends Memcached_DataObject
      * @param mixed  $v Value to lookup
      *
      * @return Yammer_state object found, or null for no hits
-     *
      */
-
     function staticGet($k, $v=null)
     {
         return Memcached_DataObject::staticGet('Yammer_state', $k, $v);
@@ -90,7 +88,6 @@ class Yammer_state extends Memcached_DataObject
      *
      * @return array array of column definitions
      */
-
     function table()
     {
         return array('id'              => DB_DATAOBJECT_INT + DB_DATAOBJECT_NOTNULL,
@@ -114,7 +111,6 @@ class Yammer_state extends Memcached_DataObject
      *
      * @return array list of key field names
      */
-
     function keys()
     {
         return array_keys($this->keyTypes());
@@ -132,7 +128,6 @@ class Yammer_state extends Memcached_DataObject
      *         'K' for primary key: for compound keys, add an entry for each component;
      *         'U' for unique keys: compound keys are not well supported here.
      */
-
     function keyTypes()
     {
         return array('id' => 'K');
@@ -148,7 +143,6 @@ class Yammer_state extends Memcached_DataObject
      *
      * @return array magic three-false array that stops auto-incrementing.
      */
-
     function sequenceKey()
     {
         return array(false, false, false);
diff --git a/plugins/YammerImport/classes/Yammer_user.php b/plugins/YammerImport/classes/Yammer_user.php
index f6fcd6c3cb..8139613347 100644
--- a/plugins/YammerImport/classes/Yammer_user.php
+++ b/plugins/YammerImport/classes/Yammer_user.php
@@ -48,7 +48,6 @@ class Yammer_user extends Yammer_common
      * @return Yammer_user object found, or null for no hits
      *
      */
-
     function staticGet($k, $v=null)
     {
         return Memcached_DataObject::staticGet('Yammer_user', $k, $v);
@@ -57,7 +56,6 @@ class Yammer_user extends Yammer_common
     /**
      * Return schema definition to set this table up in onCheckSchema
      */
-
     static function schemaDef()
     {
         return self::doSchemaDef('user_id');
@@ -71,7 +69,6 @@ class Yammer_user extends Yammer_common
      *
      * @return Yammer_user new object for this value
      */
-
     static function record($orig_id, $user_id)
     {
         return self::doRecord('Yammer_user', 'user_id', $orig_id, $user_id);
diff --git a/plugins/YammerImport/lib/sn_yammerclient.php b/plugins/YammerImport/lib/sn_yammerclient.php
index 5da1cc5e7e..2827bdc53a 100644
--- a/plugins/YammerImport/lib/sn_yammerclient.php
+++ b/plugins/YammerImport/lib/sn_yammerclient.php
@@ -19,7 +19,7 @@
 
 /**
  * Basic client class for Yammer's OAuth/JSON API.
- * 
+ *
  * @package YammerImportPlugin
  * @author Brion Vibber <brion@status.net>
  */
@@ -69,7 +69,11 @@ class SN_YammerClient
         if ($response->isOk()) {
             return $response->getBody();
         } else {
-            throw new Exception("Yammer API returned HTTP code " . $response->getStatus() . ': ' . $response->getBody());
+            // TRANS: Exeption thrown when an external Yammer system gives an error.
+            // TRANS: %1$s is an HTTP error code, %2$s is the error message body.
+            throw new Exception(sprintf(_m('Yammer API returned HTTP code %1$s: %2$s'),
+                                $response->getStatus(),
+                                $response->getBody()));
         }
     }
 
@@ -106,7 +110,8 @@ class SN_YammerClient
         $data = json_decode($body, true);
         if ($data === null) {
             common_log(LOG_ERR, "Invalid JSON response from Yammer API: " . $body);
-            throw new Exception("Invalid JSON response from Yammer API");
+            // TRANS: Exeption thrown when an external Yammer system an invalid JSON response.
+            throw new Exception(_m('Invalid JSON response from Yammer API.'));
         }
         return $data;
     }
@@ -160,7 +165,8 @@ class SN_YammerClient
     public function requestToken()
     {
         if ($this->token || $this->tokenSecret) {
-            throw new Exception("Requesting a token, but already set up with a token");
+            // TRANS: Exeption thrown when a trust relationship has already been established.
+            throw new Exception(_m('Requesting a token, but already set up with a token.'));
         }
         $data = $this->fetchApi('oauth/request_token');
         $arr = array();
diff --git a/plugins/YammerImport/lib/yammerapikeyform.php b/plugins/YammerImport/lib/yammerapikeyform.php
index b2acec4ede..72c14c30ce 100644
--- a/plugins/YammerImport/lib/yammerapikeyform.php
+++ b/plugins/YammerImport/lib/yammerapikeyform.php
@@ -53,6 +53,7 @@ class YammerApikeyForm extends Form
      */
     function formLegend()
     {
+        // TRANS: Form legend for adding details to connect to a remote Yammer API.
         $this->out->element('legend', null, _m('Yammer API registration'));
     }
 
@@ -69,6 +70,7 @@ class YammerApikeyForm extends Form
         $this->out->elementStart('fieldset');
 
         $this->out->elementStart('p');
+        // TRANS: Explanation of what needs to be done to connect to a Yammer network.
         $this->out->text(_m('Before we can connect to your Yammer network, ' .
                             'you will need to register the importer as an ' .
                             'application authorized to pull data on your behalf. ' .
@@ -81,21 +83,28 @@ class YammerApikeyForm extends Form
         $this->out->element('a',
             array('href' => 'https://www.yammer.com/client_applications/new',
                   'target' => '_blank'),
+            // TRANS: Link description to a Yammer application registration form.
             _m('Open Yammer application registration form'));
         $this->out->elementEnd('p');
 
+        // TRANS: Instructions.
         $this->out->element('p', array(), _m('Copy the consumer key and secret you are given into the form below:'));
 
         $this->out->elementStart('ul', array('class' => 'form_data'));
         $this->out->elementStart('li');
+        // TRANS: Field label for a Yammer consumer key.
         $this->out->input('consumer_key', _m('Consumer key:'), common_config('yammer', 'consumer_key'));
         $this->out->elementEnd('li');
         $this->out->elementStart('li');
+        // TRANS: Field label for a Yammer consumer secret.
         $this->out->input('consumer_secret', _m('Consumer secret:'), common_config('yammer', 'consumer_secret'));
         $this->out->elementEnd('li');
         $this->out->elementEnd('ul');
 
-        $this->out->submit('submit', _m('Save'), 'submit', null, _m('Save these consumer keys'));
+        // TRANS: Button text for saving a Yammer API registration.
+        $this->out->submit('submit', _m('BUTTON','Save'),
+                           // TRANS: Button title for saving a Yammer API registration.
+                           'submit', null, _m('Save the entered consumer key and consumer secret.'));
 
         $this->out->elementEnd('fieldset');
     }
diff --git a/plugins/YammerImport/lib/yammerauthinitform.php b/plugins/YammerImport/lib/yammerauthinitform.php
index 9f48fd82a5..c123bbbb9d 100644
--- a/plugins/YammerImport/lib/yammerauthinitform.php
+++ b/plugins/YammerImport/lib/yammerauthinitform.php
@@ -45,6 +45,7 @@ class YammerAuthInitForm extends Form
      */
     function formLegend()
     {
+        // TRANS: Form legend.
         $this->out->element('legend', null, _m('Connect to Yammer'));
     }
 
@@ -59,8 +60,12 @@ class YammerAuthInitForm extends Form
         $this->out->hidden('subaction', 'authinit');
 
         $this->out->elementStart('fieldset');
-        $this->out->submit('submit', _m('Start authentication'), 'submit', null, _m('Request authorization to connect to Yammer account'));
-        $this->out->submit('change-apikey', _m('Change API key'));
+        // TRANS: Button text for starting Yammer authentication.
+        $this->out->submit('submit', _m('BUTTON','Start authentication'),
+                           // TRANS: Button title for starting Yammer authentication.
+                           'submit', null, _m('Request authorization to connect to a Yammer account.'));
+        // TRANS: Button text for starting changing a Yammer API key.
+        $this->out->submit('change-apikey', _m('BUTTON','Change API key'));
         $this->out->elementEnd('fieldset');
     }
 
diff --git a/plugins/YammerImport/lib/yammerauthverifyform.php b/plugins/YammerImport/lib/yammerauthverifyform.php
index e119be96f7..bb82eba6ae 100644
--- a/plugins/YammerImport/lib/yammerauthverifyform.php
+++ b/plugins/YammerImport/lib/yammerauthverifyform.php
@@ -53,6 +53,7 @@ class YammerAuthVerifyForm extends Form
      */
     function formLegend()
     {
+        // TRANS: Form legend.
         $this->out->element('legend', null, _m('Connect to Yammer'));
     }
 
@@ -69,6 +70,7 @@ class YammerAuthVerifyForm extends Form
         $this->out->elementStart('fieldset');
 
         $this->out->elementStart('p');
+        // TRANS: Form instructions.
         $this->out->text(_m('Follow this link to confirm authorization at Yammer; you will be prompted to log in if necessary:'));
         $this->out->elementEnd('p');
 
@@ -84,18 +86,24 @@ class YammerAuthVerifyForm extends Form
         $this->out->element('a',
             array('href' => $this->runner->getAuthUrl(),
                   'target' => '_blank'),
+            // TRANS: Link description for a link in an external Yammer system.
             _m('Open Yammer authentication window'));
         $this->out->elementEnd('p');
-        
+
+        // TRANS: Form instructions.
         $this->out->element('p', array(), _m('Copy the verification code you are given below:'));
 
         $this->out->elementStart('ul', array('class' => 'form_data'));
         $this->out->elementStart('li');
+        // TRANS: Field label.
         $this->out->input('verify_token', _m('Verification code:'));
         $this->out->elementEnd('li');
         $this->out->elementEnd('ul');
-        
-        $this->out->submit('submit', _m('Continue'), 'submit', null, _m('Save code and begin import'));
+
+        // TRANS: Button text for saving  Yammer authorisation data and starting Yammer import.
+        $this->out->submit('submit', _m('BUTTON','Continue'),
+                           // TRANS: Button title for saving  Yammer authorisation data and starting Yammer import.
+                           'submit', null, _m('Save the verification code and begin import.'));
         $this->out->elementEnd('fieldset');
     }
 
diff --git a/plugins/YammerImport/lib/yammerimporter.php b/plugins/YammerImport/lib/yammerimporter.php
index 93bc96d529..ffc88ab473 100644
--- a/plugins/YammerImport/lib/yammerimporter.php
+++ b/plugins/YammerImport/lib/yammerimporter.php
@@ -34,7 +34,7 @@ class YammerImporter
 
     /**
      * Load or create an imported profile from Yammer data.
-     * 
+     *
      * @param object $item loaded JSON data for Yammer importer
      * @return Profile
      */
@@ -180,7 +180,8 @@ class YammerImporter
     function prepUser($item)
     {
         if ($item['type'] != 'user') {
-            throw new Exception('Wrong item type sent to Yammer user import processing.');
+            // TRANS: Exception thrown when a non-user item type is used, but expected.
+            throw new Exception(_m('Wrong item type sent to Yammer user import processing.'));
         }
 
         $origId = $item['id'];
@@ -227,6 +228,7 @@ class YammerImporter
             $bio[] = $item['summary'];
         }
         if (!empty($item['expertise'])) {
+            // TRANS: Used as a prefix for the Yammer expertise field contents.
             $bio[] = _m('Expertise:') . ' ' . $item['expertise'];
         }
         $options['bio'] = implode("\n\n", $bio);
@@ -262,7 +264,8 @@ class YammerImporter
     function prepGroup($item)
     {
         if ($item['type'] != 'group') {
-            throw new Exception('Wrong item type sent to Yammer group import processing.');
+            // TRANS: Exception thrown when a non-group item type is used, but expected.
+            throw new Exception(_m('Wrong item type sent to Yammer group import processing.'));
         }
 
         $origId = $item['id'];
@@ -277,7 +280,6 @@ class YammerImporter
 
         $avatar = $item['mugshot_url']; // as with user profiles...
 
-
         $options['mainpage'] = common_local_url('showgroup',
                                    array('nickname' => $options['nickname']));
 
@@ -285,7 +287,7 @@ class YammerImporter
         $options['homepage'] = '';
         $options['location'] = '';
         $options['aliases'] = array();
-        // @fixme what about admin user for the group?
+        // @todo FIXME: What about admin user for the group?
 
         $options['local'] = true;
         return array('orig_id' => $origId,
@@ -303,7 +305,8 @@ class YammerImporter
     function prepNotice($item)
     {
         if (isset($item['type']) && $item['type'] != 'message') {
-            throw new Exception('Wrong item type sent to Yammer message import processing.');
+            // TRANS: Exception thrown when a non-message item type is used, but expected.
+            throw new Exception(_m('Wrong item type sent to Yammer message import processing.'));
         }
 
         $origId = $item['id'];
@@ -430,7 +433,9 @@ class YammerImporter
         $url = preg_replace('/_small(\..*?)$/', '$1', $url);
 
         if (!common_valid_http_url($url)) {
-            throw new ServerException(sprintf(_m("Invalid avatar URL %s."), $url));
+            // TRANS: Server exception thrown when an avatar URL is invalid.
+            // TRANS: %s is the invalid avatar URL.
+            throw new ServerException(sprintf(_m('Invalid avatar URL %s.'), $url));
         }
 
         // @fixme this should be better encapsulated
@@ -438,7 +443,9 @@ class YammerImporter
         $temp_filename = tempnam(sys_get_temp_dir(), 'listener_avatar');
         try {
             if (!copy($url, $temp_filename)) {
-                throw new ServerException(sprintf(_m("Unable to fetch avatar from %s."), $url));
+                // TRANS: Server exception thrown when an avatar could not be fetched.
+                // TRANS: %s is the failed avatar URL.
+                throw new ServerException(sprintf(_m('Unable to fetch avatar from %s.'), $url));
             }
 
             $id = $dest->id;
diff --git a/plugins/YammerImport/lib/yammerprogressform.php b/plugins/YammerImport/lib/yammerprogressform.php
index 9bf8332261..0b73472a4d 100644
--- a/plugins/YammerImport/lib/yammerprogressform.php
+++ b/plugins/YammerImport/lib/yammerprogressform.php
@@ -60,39 +60,92 @@ class YammerProgressForm extends Form
 
         $labels = array(
             'init' => array(
-                'label' => _m("Initialize"),
+                // TRANS: Field label for a Yammer import initialise step.
+                'label' => _m('Initialize'),
+                // TRANS: "In progress" description.
                 'progress' => _m('No import running'),
+                // TRANS: "Complete" description for initialize state.
                 'complete' => _m('Initiated Yammer server connection...'),
             ),
             'requesting-auth' => array(
+                // TRANS: Field label for a Yammer import connect step.
                 'label' => _m('Connect to Yammer'),
+                // TRANS: "In progress" description.
                 'progress' => _m('Awaiting authorization...'),
+                // TRANS: "Complete" description for connect state.
                 'complete' => _m('Connected.'),
             ),
             'import-users' => array(
+                // TRANS: Field label for a Yammer user import users step.
                 'label' => _m('Import user accounts'),
-                'progress' => sprintf(_m("Importing %d user...", "Importing %d users...", $userCount), $userCount),
-                'complete' => sprintf(_m("Imported %d user.", "Imported %d users.", $userCount), $userCount),
+                // TRANS: "In progress" description.
+                // TRANS: %d is the number of users to be imported.
+                'progress' => sprintf(_m('Importing %d user...',
+                                         'Importing %d users...',
+                                         $userCount),
+                                      $userCount),
+                // TRANS: "Complete" description for step.
+                // TRANS: %d is the number of users imported.
+                'complete' => sprintf(_m('Imported %d user.',
+                                         'Imported %d users.',
+                                         $userCount),
+                                      $userCount),
             ),
             'import-groups' => array(
+                // TRANS: Field label for a Yammer group import step.
                 'label' => _m('Import user groups'),
-                'progress' => sprintf(_m("Importing %d group...", "Importing %d groups...", $groupCount), $groupCount),
-                'complete' => sprintf(_m("Imported %d group.", "Imported %d groups.", $groupCount), $groupCount),
+                // TRANS: "In progress" description.
+                // TRANS: %d is the number of groups to be imported.
+                'progress' => sprintf(_m('Importing %d group...',
+                                         'Importing %d groups...',
+                                         $groupCount),
+                                      $groupCount),
+                // TRANS: "Complete" description for step.
+                // TRANS: %d is the number of groups imported.
+                'complete' => sprintf(_m('Imported %d group.',
+                                         'Imported %d groups.',
+                                         $groupCount),
+                                      $groupCount),
             ),
             'fetch-messages' => array(
+                // TRANS: Field label for a Yammer import prepare notices step.
                 'label' => _m('Prepare public notices for import'),
-                'progress' => sprintf(_m("Preparing %d notice...", "Preparing %d notices...", $fetchedCount), $fetchedCount),
-                'complete' => sprintf(_m("Prepared %d notice.", "Prepared %d notices.", $fetchedCount), $fetchedCount),
+                // TRANS: "In progress" description.
+                // TRANS: %d is the number of notices to be prepared for import.
+                'progress' => sprintf(_m('Preparing %d notice...',
+                                         'Preparing %d notices...',
+                                         $fetchedCount),
+                                      $fetchedCount),
+                // TRANS: "Complete" description for step.
+                // TRANS: %d is the number of notices prepared for import.
+                'complete' => sprintf(_m('Prepared %d notice.',
+                                         'Prepared %d notices.',
+                                         $fetchedCount),
+                                      $fetchedCount),
             ),
             'save-messages' => array(
+                // TRANS: Field label for a Yammer import notices step.
                 'label' => _m('Import public notices'),
-                'progress' => sprintf(_m("Importing %d notice...", "Importing %d notices...", $savedCount), $savedCount),
-                'complete' => sprintf(_m("Imported %d notice.", "Imported %d notices.", $savedCount), $savedCount),
+                // TRANS: "In progress" description.
+                // TRANS: %d is the number of notices to be imported.
+                'progress' => sprintf(_m('Importing %d notice...',
+                                         'Importing %d notices...',
+                                         $savedCount),
+                                      $savedCount),
+                // TRANS: "Complete" description for step.
+                // TRANS: %d is the number of notices imported.
+                'complete' => sprintf(_m('Imported %d notice.',
+                                         'Imported %d notices.',
+                                         $savedCount),
+                                      $savedCount),
             ),
             'done' => array(
+                // TRANS: Field label for a Yammer import done step.
                 'label' => _m('Done'),
-                'progress' => sprintf(_m("Import is complete!")),
-                'complete' => sprintf(_m("Import is complete!")),
+                // TRANS: "In progress" description for done step.
+                'progress' => sprintf(_m('Import is complete!')),
+                // TRANS: "Complete" description for done step.
+                'complete' => sprintf(_m('Import is complete!')),
             )
         );
         $steps = array_keys($labels);
@@ -105,6 +158,7 @@ class YammerProgressForm extends Form
             $classes[] = 'yammer-running';
         }
         $this->out->elementStart('fieldset', array('class' => implode(' ', $classes)));
+        // TRANS: Fieldset legend.
         $this->out->element('legend', array(), _m('Import status'));
         foreach ($steps as $step => $state) {
             if ($state == 'init') {
@@ -129,7 +183,8 @@ class YammerProgressForm extends Form
                 $this->progressBar($state,
                                    'waiting',
                                    $labels[$state]['label'],
-                                   _m("Waiting..."));
+                                   // TRANS: Progress bar status.
+                                   _m('Waiting...'));
             }
         }
         $this->out->elementEnd('fieldset');
@@ -143,11 +198,13 @@ class YammerProgressForm extends Form
         $this->out->element('div', array('class' => 'import-status'), $status);
         if ($class == 'progress') {
             if ($state == 'done') {
+                // TRANS: Button text for resetting the import state.
                 $this->out->submit('abort-import', _m('Reset import state'));
             } else {
                 if ($error) {
                     $this->errorBox($error);
                 } else {
+                    // TRANS: Button text for pausing an import.
                     $this->out->submit('pause-import', _m('Pause import'));
                 }
             }
@@ -157,11 +214,15 @@ class YammerProgressForm extends Form
 
     private function errorBox($msg)
     {
-        $errline = sprintf(_m('Encountered error "%s"'), $msg);
+        // TRANS: Error message. %s are the error details.
+        $errline = sprintf(_m('Encountered error "%s".'), $msg);
         $this->out->elementStart('fieldset', array('class' => 'import-error'));
+        // TRANS: Fieldset legend for a paused import.
         $this->out->element('legend', array(), _m('Paused'));
         $this->out->element('p', array(), $errline);
+        // TRANS: Button text for continuing a paused import.
         $this->out->submit('continue-import', _m('Continue'));
+        // TRANS: Button text for aborting a paused import.
         $this->out->submit('abort-import', _m('Abort import'));
         $this->out->elementEnd('fieldset');
     }
diff --git a/plugins/YammerImport/lib/yammerrunner.php b/plugins/YammerImport/lib/yammerrunner.php
index 3e53f3361b..04cc9c0283 100644
--- a/plugins/YammerImport/lib/yammerrunner.php
+++ b/plugins/YammerImport/lib/yammerrunner.php
@@ -123,7 +123,8 @@ class YammerRunner
     public function requestAuth()
     {
         if ($this->state->state != 'init') {
-            throw new ServerException("Cannot request Yammer auth; already there!");
+            // TRANS: Server exception thrown if a Yammer authentication request is already present.
+            throw new ServerException(_m('Cannot request Yammer auth; already there!'));
         }
 
         $data = $this->client->requestToken();
@@ -149,7 +150,8 @@ class YammerRunner
         if ($this->state() == 'requesting-auth') {
             return $this->client->authorizeUrl($this->state->oauth_token);
         } else {
-            throw new ServerException('Cannot get Yammer auth URL when not in requesting-auth state!');
+            // TRANS: Server exception thrown when requesting a Yammer authentication URL while in an incorrect state.
+            throw new ServerException(_m('Cannot get Yammer auth URL when not in requesting-auth state!'));
         }
     }
 
@@ -167,7 +169,9 @@ class YammerRunner
     public function saveAuthToken($verifier)
     {
         if ($this->state->state != 'requesting-auth') {
-            throw new ServerException("Cannot save auth token in Yammer import state {$this->state->state}");
+            // TRANS: Server exception thrown if a Yammer authentication token could not be saved in a certain import state.
+            // TRANS: %s is the import state in the which the error occurred.
+            throw new ServerException(_m('Cannot save auth token in Yammer import state %s.',$this->state->state));
         }
 
         $data = $this->client->accessToken($verifier);
@@ -324,7 +328,7 @@ class YammerRunner
         $stub->limit(20);
         $stub->orderBy('id');
         $stub->find();
-        
+
         if ($stub->N == 0) {
             common_log(LOG_INFO, "Finished saving Yammer messages; import complete!");
             $this->state->state = 'done';
@@ -353,7 +357,6 @@ class YammerRunner
         return $map->count();
     }
 
-
     /**
      * Count the number of Yammer groups we've mapped into our system!
      *
@@ -365,7 +368,6 @@ class YammerRunner
         return $map->count();
     }
 
-
     /**
      * Count the number of Yammer notices we've pulled down for pending import...
      *
@@ -377,7 +379,6 @@ class YammerRunner
         return $map->count();
     }
 
-
     /**
      * Count the number of Yammer notices we've mapped into our system!
      *
@@ -401,8 +402,8 @@ class YammerRunner
     /**
      * Record an error condition from a background run, which we should
      * display in progress state for the admin.
-     * 
-     * @param string $msg 
+     *
+     * @param string $msg
      */
     public function recordError($msg)
     {
@@ -428,7 +429,7 @@ class YammerRunner
 
     /**
      * Get the last recorded background error message, if any.
-     * 
+     *
      * @return string
      */
     public function lastError()
diff --git a/plugins/YammerImport/scripts/yammer-import.php b/plugins/YammerImport/scripts/yammer-import.php
index b4aa921e50..22b6422195 100644
--- a/plugins/YammerImport/scripts/yammer-import.php
+++ b/plugins/YammerImport/scripts/yammer-import.php
@@ -4,7 +4,6 @@ if (php_sapi_name() != 'cli') {
     die('no');
 }
 
-
 define('INSTALLDIR', dirname(dirname(dirname(dirname(__FILE__)))));
 
 $longoptions = array('verify=', 'reset');