They did it at my roomate's high school, but not at mine. I think it's a good idea, it seems extreme...but so does becoming mentally retarded or dying because you couldn't ask for a ride.
Once when I was at the grocery store with my mom and told me about this guy who was working there. He was one of the smartest kids in his school and on prom night he went out drinking and tried to drive himself home. He got in a wreck and now will never be able to have a true career or probably take care of himself. That was enough to make me think twice!