--- activity_comments.module	Fri Dec 11 14:25:49 2009
+++ activity_comments.module	Fri Dec 11 12:51:23 2009
@@ -203,6 +203,7 @@
   $record->aid = $form_state['values']['aid'];
   $record->timestamp = time();
   drupal_write_record('activity_comments', $record);
+  drupal_alter('activity_comment', $record);
   db_query("UPDATE {activity_comments_stats} SET comment_count = comment_count + 1, changed = %d WHERE aid = %d", time(), $form['aid']['#value']);
 }