Can I include a list of sub-menu pages in the content of the parent page?
By some coincidence, there is an article on how to embed a block in the middle of your node body content on Drupal Planet today.

It seems to me, though, that if you put the block at the top of your content and floated it with css, maybe with a border attribute, the result would perhaps be better than adding content to an arbitrary location inside the content.