I've created a custom sidebar that grabs the post parent's pages:
query_posts("post_type=page&post_parent=6");
I'd like to grab the title of the post_parent (i.e. "About"). the_title won't work because it's the title of the child pages.
How can I output the post_parent title?
It looks like you've already got the ID of the parent post, so you can just use this:
<?php
$parent_post_id = 6;
$parent_post = get_post($parent_post_id);
$parent_post_title = $parent_post->post_title;
echo $parent_post_title;
?>
(Insert your parent post id at $parent_post_id)