I applaud them for their simple ingenuity. Even with my privacy settings to the max, my basic personal information is still displayed (profile pic, name, city and state, etc...). Facebook has successfully de-anonymized a large portion of internet users.
GNUnet here I come! (a social networking application on top of GNUnet? that would be awesome)
Old post. Also, there is a startup that does exactly this. They turn an email address into a social connection - http://flowtown.com
Actually there is more than one service offering this and most of them are built on top of the Rapleaf API: http://www.rapleaf.com/