The Beta for the Microsoft Research Kinect for Windows SDK is now available at the project website.

 Be sure to note that the license for this technology is for non-commercial use only.

Update: Microsoft announced that there will be a Kinect for Windows commercial program next year (2012). See also this recent blog post.

See http://www.kinectforwindows.org/

Update 2: Kinect for Windows 1.5 is now available.