OpenCV does detection. I haven't found anything to do recognition, I suspect it's a much harder problem. It's not open source, but in the past I've used picas

OpenCV does detection. I haven't found anything to do recognition, I suspect it's a much harder problem. It's not open source, but in the past I've used picassa to do recognition. You let it run, interact with it to resolve ambiguities, and then pull the face assignments/rectangles out of the .picasa.ini files that it drops next to your photos. (There was also a contacts.xml file somewhere that provided the mapping from a guid to name/email.)