Index: wp-comments-post.php
===================================================================
--- wp-comments-post.php	(revision 2837)
+++ wp-comments-post.php	(working copy)
@@ -37,9 +37,14 @@
+add_action('comment_problem','wp_comment_error_message');
+function wp_comment_error_message($comment_msg) {
+	die($comment_msg);
+}
+
if ( get_settings('require_name_email') && !$user_ID ) {
	if ( 6 > strlen($comment_author_email) || '' == $comment_author )
-		die( __('Error: please fill the required fields (name, email).') );	
+		do_action( 'comment_problem', __('Error: please fill the required fields (name, email).') );
	elseif ( !is_email($comment_author_email))
-		die( __('Error: please enter a valid email address.') );
+		do_action( 'comment_problem', __('Error: please enter a valid email address.') );
}

if ( '' == $comment_content )
-	die( __('Error: please type a comment.') );
+	do_action('comment_problem', __('Error: please type a comment.') );