File this under cool shit we probably won't see for a long time. Apple just recently filed filed an expanded patent application for a system that would detect hand/head motion around a computer and let you manipulate projected image controls.
There are a whole bunch of systems at work here, and they all sound cool. Hand-controls, such as gestures, would be read with the help of an infrared laser which creates a volume of space (i.e. a 3D box). Anything your hands do within that box can be read and interpreted by the computer. But aside from gestures, how would you make fine adjustments? Apple has a plan for that, too.
The patent doc also talks of a system for projecting virtual images onto surfaces (i.e. your desk) using a system of several projectors and mirrors. These images, "knobs, sliders, buttons, and so forth" would be projected into the volume of space which is being monitored by the laser. You could then manipulate these controls and receive video and audio feedback (since haptic feedback would be impossible... for now...).
The third component of awesome is the glasses-free 3D. Here Apple would employ motorized head-tracking cameras, so that a good 3D image is delivered regardless of where your head is. The camera may also be able to track head or eye motion in a way that would allow you to scroll or zoom without having to use your hands at all. Sign me up for that.
Now, keep in mind this is just a patent filing and there's no telling how this could change and evolve (after all, they filed something similar not long ago). Or it could be scrapped outright. Or it could be integrated into Apple HDTV, delivering a sort of all-in-one XBox Kinectian experience (except they don't have games, yet). Besides, we know that Apple has been looking into holographic multi-touch systems for a while. It seems like they are trying to sneak in late to a game where they currently have no foothold. All that said, none of the technological elements in this recent patent are really outside the realm of possibility—it's just a clever combination of things that exist today. I wouldn't be the least bit surprised if they have a working prototype in Cupertino already. If you enjoy sifting through the details of patents, here ya go. [Unwired View via SlashGear]