Index: wp-includes/meta.php
===================================================================
--- wp-includes/meta.php	(revision 30104)
+++ wp-includes/meta.php	(working copy)
@@ -478,8 +478,15 @@
 		$meta_cache = $meta_cache[$object_id];
 	}
 
-	if ( !$meta_key )
+	if ( !$meta_key ) {
+		if ( is_array( $meta_cache ) ) {
+			array_walk_recursive( $meta_cache, function( &$original ) {
+				$original = maybe_unserialize( $original );
+			} );
+		}
+
 		return $meta_cache;
+	}
 
 	if ( isset($meta_cache[$meta_key]) ) {
 		if ( $single )