BuddyPress.org

The only fields that show up during registration are the ones in the main group, and even then they have to be marked as required. Any other profile fields won’t show up during registration, but just like Jeff said will need to be filled in.

(Ironically enough, if you save your profile without all of the required fields filled in on the page, it still saves the data. Not sure if this is a bug or not, but I kind of like it like this actually.)

I suspect in the future there will be more selections and features as to which fields to show on registration, etc…