I started a second site with WP3.01, added BP, then added some test pages. Otherwise, this second installation is totally clean.
All top level pages show on the menu as expected. However, if I put a page under another page as parent, the new subpage does not show as a submenu. Submenus do not appear.
This is independent of theme except on my first site. On my first site the submenus show up with BPDaily theme, but they do not show up under BP default theme.