The cool thing about facebook's photos is that with their API, you can pull the name->XY locations of the picture which has a person tagged to it (making the facial detection portion super easy). Then with the set of name -> faces[], training the facial recognition database becomes even easier.
Facebook it self has a even more sinister potential. Imagine they train a facial recognition database for everyone already tagged in photos on facebook. Then have a iPhone app, which you can take a picture of anyone... which would spit out the name/info/school/interests/everything. There is nothing technologically stopping this, and it will be just a matter of time.
(puts on my tin foil hat)