--- modules/comment/comment.module.orig	2009-08-11 08:39:34.000000000 -0400
+++ modules/comment/comment.module	2009-08-11 08:40:03.000000000 -0400
@@ -1235,6 +1235,8 @@ function comment_save($comment) {
     $comment->node_type = 'comment_node_' . $node->type;
   }
 
   field_attach_presave('comment', $comment);
+
+  // Allow modules to alter the comment before saving.
+  module_invoke_all('comment_presave', $comment);
 
   if ($comment->cid) {
--- modules/comment/comment.api.php.orig	2009-08-11 08:39:50.000000000 -0400
+++ modules/comment/comment.api.php	2009-08-11 08:40:32.000000000 -0400
@@ -12,6 +12,18 @@
  */
 
 /**
+ * The comment passed validation and is about to be saved.
+ *
+ * Modules may make changes to the comment before it is saved to the database.
+ *
+ * @param $comment
+ *   The comment object.
+ */
+function hook_comment_presave($comment) {
+  // Change the comment object before it is saved.
+}
+
+/**
  * The comment is being inserted.
  *
  * @param $comment