Kinect MIDI Controller is an open source project designed to let you use a Microsoft Kinect as a MIDI controller.
The the project uses Microsoft Kinect SDK to track the skeletal data.
The Kinect SDK provides the logic to detect the X and Y Co-ordinates of a user’s hands. The X & Y Co-ordinates are then scaled and converted to MIDI messages. These MIDI messages are then sent to the MIDI output port. The tool contains a .NET Wrapper for the MIDI interfacing methods provided by winmm.dll Win32 API.
Details are available the project site.