Dynamic menu highlighting and (sub)pages

The codex had a fine article on dynamic menu highlighting (http://codex.wordpress.org/Dynamic_Menu_Highlighting). It states that the described way of doing this only works with pages, but the is_*-function could also test for other conditions. I wonder if anyone found a way to use this method of menu highlighting for sub-pages: my guess is that it should be possible because the database somehow stores information on pages, children etc. The same goes for category’s: I would like to show articles in a category under the right highlighted item in the menu. Anyone with a clue?