With the ever-improving Leap Motion SDK, and some work related motivation to "yarpify" things, I got the following running after struggling with some typos in my SYSEX messages that are used to control the organ.
The above shows one simple mapping: X (left right) controls the pitch, and moving the hand forward goes from no sound, to a single stop, to a second stop that's making notes a third higher. What was immediately interesting was that the digital control of the organ is extremely fast, and glissing through in this manner created runs that are basically impossible to do on a standard keyboard (well, maybe if you practiced some two-hand technique where you can time the black notes in between the white ones...). Also, it was very apparent that a simple linear X-position to pitch is highly unnatural when you don't have the tangible feedback of a physical, rectangular keyboard.