The Nintendo Wii seems to sit in the middle of two worlds: the (old) world of solid interfaces (mouses, keyboards, buttons,...) and the coming world of virtual interfaces where we will interact with devices through gestures in the empty air with our bare hands.
While the Wii still requires you to hold a controller, Microsoft's Natal Project is one first step into the new world...
But there is more:
...and this extrapolation doesn't look too far away after all:
If you want to try the gestural interface for yourself: all you need is a webcam and the software for this site
