Is there a way to use iSight camera to control display based on motion?

I have a "weather" computer setup in my kitchen. It literally just has Doppler radar on at all times. I don't want the screen on all the time when I'm not in there for obvious reasons (burn, energy, etc.). I'd like the screen to sleep after say, an hour, and when I walk by have it come on. Any ideas how to accomplish this? Would be cool if the built in camera could somehow be used as a motion sensor.