What an interesting idea. It’s not practical in any sense, but it’s a great example of thinking out side the box and trying to do something different that is so ingrained in computer users. The main reason this would never take off has to be the lack of tactile stimulation. I am sure my beautiful scientist (*cough cough*) can back this up with some hard scientific data, but users prefer and in fact, respond quicker when they have the tactile sensation of clicking on something. One of the major compliants with the 5th gen video iPod’s is the almost entirely tacticle-less click-wheel. People like to feel what they are selecting. Nonetheless, very cool.