A new DigitalPoint Forums thread is discussing a feature on Google Image Search that most people do not know about. Did you know you can restrict your searches of images to those that just return faces?
To restrict your image searches by face only, append "&imgtype=face" to the end of the URL. Google should then show you a message that reads "Showing only images containing faces (show all images)." There is your confirmation that it works.
And it does work.
Forum discussion at DigitalPoint Forums.