My first real introduction to Microsoft's motion-controlling Project Natal occurred in a brightly-lit hotel room in LA's The Standard Hotel.
Standing in front of a television with Burnout Paradise on it, I held my hands out as if holding steering wheel and acted as if I was driving a car. It was that simple and the results were surprisingly precise.
To speed up I moved my foot forward, to slow down I moved my foot back and to kick the car into turbo, I grabbed an imaginary stick shift and acted as if I was pushing it forward.
While the turbo activates fairly easily, the gas controls were the game's weakest link. Essentially the gas was an on and off switch. It was either full speed or stop.
The person demonstrating the game pointed out that it was really just a tech demo to show off the game's potential. He said that because the game wasn't made for the tech, there were some issues.
I drove around a bit of the city using my imaginary steering wheel, weaving between cars with no problem, tearing around sharp corners and deliberately plowing into other vehicles. It felt a bit weird to hold my arms out straight in front of me and pretend to drive, but the results were so lag free, so responsive that it didn't bother me.
To prove there were no tricks behind the tech, the team had the system sitting out completely exposed. Developers had a make-shift sensor sitting on front of a television. Sitting on the floor next to the TV was an Xbox 360 and a second television showing the images the camera was seeing and how it was processing those images.
The screen showed my image as a silhouette of red and orange. A bunch of little boxes marked points on my face and body. In another window my live image was being converted into an animated stick figure, showing me moving around in real time.
All of that was just the system's input, the software took that input and removed lag to make sure that your motions were fed through the system to the game's controls will little to no slow down.
Of course all of that will be happening behind the scenes when Project Natal hits consoles.