4th
Microsoft Natal - promising but surrounded in a lot of hype. With multi-player full-body tracking, face and voice recognition it’s extremely ambitious.
The demos here are (on inspection) only using the depth map - no full-body tracking or multiple players.
It’s obvious that this is very early in development and is being demoed largely as a spoiler for Sony’s motion controller announcements. According to philosophistry, MS only just recently aqcuired the technology (using time of flight cameras) in March 2007 through their purchase of 3DV Systems (see their gallery here).
There’s a lot of work for MS ahead if they are to deliver what their marketing department has promised but when (if) they do it’s going to be amazing!