MyHeritage, a genealogy web site, claims it can automatically tag photos of people. It uses face recognition to find faces in uploaded photos, then gets you to identify them. The idea is that you only identify each person once, and it can automatically tag other photos of that person for you.
MyHeritage organizes photos based on who appears in them.
MyHeritage is able to identify and tag people you’ve already told it about, in all your other photos, and in any new photos you’ll upload, automatically.
I’ve only tested it very slightly, but it does seem to work to some degree. It’s fairly slow to complete the facial recognition step, understandably, but it really does seem to be trying to recognise individual people.
Only a matter of time before it becomes more wide-spread, I’m sure.