Index: wp-includes/post.php
===================================================================
--- wp-includes/post.php	(revision 11262)
+++ wp-includes/post.php	(working copy)
@@ -1613,8 +1613,11 @@
  * @return int 0 on failure, Post ID on success.
  */
 function wp_update_post($postarr = array()) {
-	if ( is_object($postarr) )
+	if ( is_object($postarr) ) {
+		// non-escaped post was passed
 		$postarr = get_object_vars($postarr);
+		$postarr = add_magic_quotes($postarr);
+	}
 
 	// First, get all of the original fields
 	$post = wp_get_single_post($postarr['ID'], ARRAY_A);