Index: wp-includes/functions-post.php
===================================================================
--- wp-includes/functions-post.php	(revision 3321)
+++ wp-includes/functions-post.php	(working copy)
@@ -136,8 +136,8 @@
 			post_name = '$post_name',
 			to_ping = '$to_ping',
 			pinged = '$pinged',
-			post_modified = '$post_date',
-			post_modified_gmt = '$post_date_gmt',
+			post_modified = '".current_time('mysql')."',
+			post_modified_gmt = '".current_time('mysql',1)."',
 			post_parent = '$post_parent',
 			menu_order = '$menu_order'
 			WHERE ID = $post_ID");
@@ -283,6 +283,9 @@
 	if ( !isset($post_password) )
 		$post_password = '';
 
+	$post_modified = ( isset($edit_date) ) ? current_time('mysql') : $post_date;
+	$post_modified_gmt = ( isset($edit_date)) ? current_time('mysql',1) : $post_date_gmt;
+
 	if ($update) {
 		$wpdb->query(
 			"UPDATE $wpdb->posts SET
@@ -298,8 +301,8 @@
 			post_password = '$post_password',
 			post_name = '$post_name',
 			to_ping = '$to_ping',
-			post_modified = '$post_date',
-			post_modified_gmt = '$post_date_gmt',
+			post_modified = '$post_modified',
+			post_modified_gmt = '$post_modified_gmt',
 			post_parent = '$post_parent',
 			menu_order = '$menu_order',
 			post_mime_type = '$post_mime_type',