I am trying to create a list of sibling pages (not posts) in WordPress to populate a page\'s sidebar. The code I\'ve written successfully returns a page\'s parent\'s title. >
$post->post_parent is giving you the parent ID, $post->ID will give you the current page ID. So, the following will list a page's siblings:
$post->post_parent
$post->ID
wp_list_pages(array( 'child_of' => $post->post_parent, 'exclude' => $post->ID ))