Kinect is a no doubt going to be a game changer. If for no other reason than it places the Xbox 360 in the same arena as the Nintendo Wii, and even raises Nintendo's hand. In terms of show-stopping prowess the likes of Dance Central, Kinect Sports, and Kinect Adventures get the message across: it's about body control. What really will be interesting is if Microsoft can take the system beyond what it showed people, and use it to create comfortably interactive experiences - ones that are subtle, rather than show-stopping.
Cleverly controlled menu systems that you can understand and control instinctively without having to reach for the remote control (because there isn't one any more). Microsoft Kinect will be released in time for Christmas.