Index: wp-includes/functions.php
===================================================================
--- wp-includes/functions.php	(revision 18444)
+++ wp-includes/functions.php	(working copy)
@@ -3202,8 +3202,8 @@
  */
 function wp_list_pluck( $list, $field ) {
 	foreach ( $list as $key => $value ) {
-		$value = (array) $value;
-		$list[ $key ] = $value[ $field ];
+		if ( is_object( $value ) ) $list[ $key ] = $value->$field;
+		else $list[ $key ] = $value[ $field ];
 	}
 
 	return $list;