Microsoft has recently open sourced on CodePlex 22 code samples under the Apache 2.0 license. The samples which are also included in the Kinect for Windows Toolkit show how to make use of various Kinect features: Audio, Basic Interactions, Colors, Depth, Face Tracing, Infrared, Slideshow Gestures, Speech, WPF, XNA, and others.
The samples are in mostly in C# and C++, and a handful of them are in VB. They make use of WPF or DirectX technologies.
Although the code can be forked from its CodePlex Git repository, Microsoft does not accept any contributions yet. They do mention investigating how it could be done in the future.
Kinect development requires Visual Studio 2010 or 2012, .NET 4.0 or 4.5, Kinect for Windows SDK and Kinect for Windows Toolkit.
Although Kinect started as a gaming device, it is currently being used or under research for a variety of projects such as Autodesk modeling tool, controlling gloves, hand tracking in 3D, Google TV controller, putting patients at ease, apparel shopping, and others.