I've found that, as a general rule, if you're tempted to ask, "Why hasn't anybody thought of this yet?" you're too late. I was frustrated the other day as I was reading in the newspaper about yet another non-tech-origins group filing for patents on old ideas with new technology (in this case, using a Wiimote to control the playback of a MIDI score). Naturally, the "inventors" were wondering why nobody'd ever done that before, and yet solo performers and Arduino-type digital artists have been using various types of sensors to do the same thing for quite a while.