Index: wp-trackback.php
===================================================================
--- wp-trackback.php	(revision 4661)
+++ wp-trackback.php	(working copy)
@@ -90,6 +90,8 @@
 
 	$commentdata = compact('comment_post_ID', 'comment_author', 'comment_author_email', 'comment_author_url', 'comment_content', 'comment_type');
 
+	$commentdata = apply_filters('trackback_extend_comment', $commentdata, $_POST);
+
 	wp_new_comment($commentdata);
 
 	do_action('trackback_post', $wpdb->insert_id);