Microsoft are releasing the Kinect unit specifically for Windows users on February 1st.
The hardware, and accompanying software, is currently listed at a price of $249, which is a big jump from the Kinect unit for Xbox360. Whilst they are essentially the same, the Xbox360 hardware is subsidised by the selling of Kinect games and such, hence the lower price.
Perhaps the most interesting enhancement of the Kinect for Windows unit will the the “Near Mode”. This has adjusted the camera depth to see objects as close as 50cm without losing any accuracy or precision.