I've activated BuddyPress on my test site - http://stevelescure.net/wp/ - and have been experimenting with it a bit. Pretty neat.
I would imagine that most users would prefer to log-in using their Facebook ID so they don't have yet another ID/password to remember, so I installed the WP-FB-Autoconnnect plugin. The author of that plugin said, depending on the theme, the Facebook log-in might appear adjacent to the BuddyPress login. No dice with CommentPress, understandably. The only other option is to use a widget, but with CommentPress it would have to go on in the footer, so that doesn't work either.
I know it's unlikely, but is there an easy way to allow users to log-in to BuddyPress via Facebook that i perhaps don't know about? Thought I'd ask. It seems to use WP-FB-Autoconnect i'd have to modify the BuddyPress code.