PolarRose.com is beta testing their photo recognition software that they have implemented into an image search engine. Their annoucement has stirred a little controversy as far as privacy and security goes.
The engine could address a solid niche on the web. Obviously use of robots.txt files can block people's personal info, or just wait until someone in Australia uses the system to find you and sue (see the story below about the court ruling).
Using what Tim O'Reilly calls 'bionic software', "Polar Rose relies on a combination of our unique face recognition algorithms and the collective intelligence of our users.
The face recognition technology used was originally developed by CTO Jan Erik Solem during his M.Sc and Ph.D. stints at the universities of Lund and MalmÃ¶ in southern Sweden. It's unique in that we are able to extract 3D information from regular 2D images, an approach that radically improves the short-comings of existing face recognition approaches.
However, we don't and can't rely exclusively on face recognition, but also harness the collective intelligence of our users who help train our software and tag names on people we haven't seen before" according to their website.