Index: wp-includes/comment.php
===================================================================
--- wp-includes/comment.php	(revision 18324)
+++ wp-includes/comment.php	(working copy)
@@ -1355,7 +1355,7 @@
 		$post = &get_post($commentdata['comment_post_ID']); // Don't notify if it's your own comment
 
 		if ( get_option('comments_notify') && $commentdata['comment_approved'] && ( ! isset( $commentdata['user_id'] ) || $post->post_author != $commentdata['user_id'] ) )
-			wp_notify_postauthor($comment_ID, isset( $commentdata['comment_type'] ) ? $commentdata['comment_type'] : '' );
+			wp_notify_postauthor( $comment_ID );
 	}
 
 	return $comment_ID;
@@ -1391,8 +1391,7 @@
 		case '1':
 			$status = '1';
 			if ( get_option('comments_notify') ) {
-				$comment = get_comment($comment_id);
-				wp_notify_postauthor($comment_id, $comment->comment_type);
+				wp_notify_postauthor( $comment_id );
 			}
 			break;
 		case 'spam':
Index: wp-includes/pluggable.php
===================================================================
--- wp-includes/pluggable.php	(revision 18324)
+++ wp-includes/pluggable.php	(working copy)
@@ -1040,10 +1040,13 @@
  * @since 1.0.0
  *
  * @param int $comment_id Comment ID
- * @param string $comment_type Optional. The comment type either 'comment' (default), 'trackback', or 'pingback'
+ * @param string $deprecated Not used
  * @return bool False if user email does not exist. True on completion.
  */
-function wp_notify_postauthor( $comment_id, $comment_type = '' ) {
+function wp_notify_postauthor( $comment_id, $deprecated = null ) {
+	if ( null !== $deprecated )
+		_deprecated_argument( __FUNCTION__, '3.3' );
+
 	$comment = get_comment( $comment_id );
 	$post    = get_post( $comment->comment_post_ID );
 	$author  = get_userdata( $post->post_author );
@@ -1066,7 +1069,7 @@
 	// we want to reverse this for the plain text arena of emails.
 	$blogname = wp_specialchars_decode(get_option('blogname'), ENT_QUOTES);
 
-	if ( empty( $comment_type ) ) $comment_type = 'comment';
+	$comment_type = $comment->comment_type ? $comment->comment_type : 'comment';
 
 	if ('comment' == $comment_type) {
 		$notify_message  = sprintf( __( 'New comment on your post "%s"' ), $post->post_title ) . "\r\n";