I attended a gaming technology convention about 5 years ago in which Griffin had a booth where they were demonstrating the Biometrica technology. The way it works - or at least the way it worked at the time was; the camera would focus on the subject, and the computer would pull up about a dozen or so images of the people in their database who MOST closely resembled the subject in question.
As a test, I stepped in front of the camera and of the 12 images it pulled up, it did NOT find a picture of me. (and my picture definitely IS in Griffin's database, no question about it) :grin:
Yes, I always wear a cap (as do MOST APs, of course).
I've also been told that wearing eyeglasses WITHOUT anti-glare coating helps. I ALWAYS refuse the coating when I get new glasses; so far (though I can't say with 100% certainty) I don't believe facial recognition technology has ever gotten me busted YET.