The syncing at registration is the primary benefit of the component along with allowing for single-sign on return (or automatic if already logged into Facebook).
As for sharing photo albums, and the other things you mention, there is development being made to add more features for more cross-community communication. However, nothing has been announced yet. If you're a developer yourself, we can help you create any functions your looking for which you can then distribute for others to use as well.
what does this really do?
