WOW people taking a U-turn, don't jump on carl because he is telling the truth. Natal is being hyped as a controller free interface and using peripherals completely defeats the purpose. It's no better at all than the PS3 dildo stick.
If you cannot find a reason why shooters will work without a physical object that is fine but don't start insulting others because you can't think of anything. Gosh some of you. :(