It’s common knowledge that Project Natal is Microsoft’s next big thing.
The Idea of motion control in games is hardly new,but Natal is trying to take it to the next level using advanced tech to respond to almost every movement of your body.

Here we appear to have leaked footage of Natal being used to control Half Life 2,though the video lacks audio it looks as though the person using Natal was unaware of the camera.

Whether this is truly leaked,deliberately leaked or fake is now yet known.
However the implications in the video are still amazing as you watch the user move the in-game character around using nothing but hand motions.