The AirPiano is project by Omer Yosha, an Interface Design student from the FH Potsdam (Germany).

The AirPiano is an innovative musical interface which allows playing and controlling software instruments simply by moving hands in the air.

Above the AirPiano is a virtual matrix of keys and faders, each assigned with MIDI messages and ready to be triggered. The length of a triggered note is equivalent to the time a hand
is placed on the corresponding virtual key.
This is also confirmed by LED feedback.
The AirPiano Software allows easy setup, loading/saving presets and transposing notes.

The AirPiano is still in its prototype phase and its concept of a virtual matrix might eventually be used for other applications and purposes.
The AirPiano concept is filled as a Provisional U.S. Patent Application (Number: 60/989,986).

In this video he uses his AirPiano to control Ableton Live.

found at Create Digital Music