The free version of iisu is strictly a "non-commercial" SDK, though a full, commercial version can be purchased. The dev kit offers tools for building both games and applications, and includes Unity 3D and Flash support. Interested parties can get the ball rolling by applying for a free license on SoftKinetic's application page.
Between SoftKinetic's SDK and those from Evoluce, PrimeSense and even Microsoft itself, there will soon be, like, so many SDKs available for Kinect. We're gonna start stretching right now in preparation for the eventual results.