In reply to Beau Lebens.

To use o2, you have to use a compatible theme, and then o2 actually takes over the entire content area of the site. It powers everything on that WP install (pages included). It includes support for Menus and widgets (in a single sidebar) in the current theme (P2).

If you want to run BuddyPress and other things, I'd suggest trying it out either on a multi-site install, or a separate WP install. Nothing like that has been extensively tested though, so "continue at your own risk" :)