"The Flo Control Project uses a webcam to do facial recognition as authentication to open a cat door for the family cat. If the cat has something in its mouth or some other animal approaches the door, it does not open. If the cat approaches with nothing in its mouth, then the door unlocks."
Is there anything a nerd can't do?
Found on the wonderful, gotta-look-at-it-every-single-day website, Boing Boing.