How about this:

An ultra portable piano controller -
You'll move your hands on whatever surface you got, e.g. your desk, (perhaps accompanied by folding drawing of piano keys)
or even - in the air (though the former seems more convenient).
It seems to measure every nuance of the hand movement, so it can also measure finger speed, and therefor - velocity ...

That would suck. When playing the piano in a lot of cases you depend on rebound of the keys. Your desk will not rebound back at ya.

An ultra portable piano controller -
You'll move your hands on whatever surface you got, e.g. your desk, (perhaps accompanied by folding drawing of piano keys)
or even - in the air (though the former seems more convenient).
It seems to measure every nuance of the hand movement, so it can also measure finger speed, and therefor - velocity ...

On missing the sustain pedal

-- Eran

https://live.leapmotion.com/about/

Overview article from the CNN Tech section, derived from a mashable.com article:

http://www.cnn.com/2012/05/22/tech/inno...index.html

Original article with video demonstrations:

http://mashable.com/2012/05/21/leap-motion/

Good for changing partial strengths, raising the lid, moving mics, etc? Possibly for even sounding a note or interval without a keyboard?