I finally got access to Polar Rose (news story), an image search site I've been looking forward to trying. This early version of the product isn't terribly compelling, though. Today, Polar Rose can pick out faces in photos. It doesn't tell you who's who, though. The idea is that Web users who have the Polar Rose browser plugin do that.
On the other side of the product is a search engine for pictures of people. If you want to find a picture of someone, and that person has been tagged by users, Polar Rose will show you all the pictures that match.
Future versions of the product will actually do facial recognition, I'm told, although the company isn't disclosing when that function will go into beta. This is the holy grail of visual search, of course. Last year, Riya demoed a tool that was supposed to do what Polar Rose is still building, but Riya eventually gave up and moved into image search for commerce (it finds shoes that look alike, for example).