Today I’m going to the Y Combinator Demo Day, where the startup companies nurtured by this hi-tech hothouse present their wares and their business plans to the Valley’s smartest investors. There are over 60 companies this time around, and since I haven’t dropped in the Winter 2012 class, I have very little idea what to expect. But I know of at least one company that’s bound to get some notice: Flutter.

Flutter is a Mac OS app that makes your webcam into sort of an Xbox Kinect, monitoring its field of vision for movement and interpreting actions. Once Flutter is installed, you can use specified gestures to get the same result as key commands from the mouse or keyboard.

If Flutter’s claims about the deep technical basis for its performance are true, then Apple should reach into the Cupertino equivalent of Forth Worth for the cash needed to snap up the startupRight now, there aren’t many uses, but the first ones, working with Spotify and iTunes, are nifty proofs of concept. By holding up your hand, palm forward, between one and six feet from the webcam, you can pause or play a song. (It actually recognizes the shape of a hand — putting a paper in front of the screen doesn’t trick it.) You can also do the the same with iTunes video playback — YouTube and Netflix are next. Next comes recognition of a swipe gesture to skip songs — and also to advance slides in PowerPoint. Your next preso won't need a remote! (But if you swat a fly, everything goes to hell.)

According to Flutter’s co-founder Mehul Nariyawala, though, the sky’s the limit for the variety of hand motions Flutter recognizes and the number of applications that will support it. He says that in comparison to Kinect, which measures big movements that commonly involve vigorous activity with arms and legs, Flutter detects gestures. You won’t use it to lose weight, but you can eventually use it to replace the old model of navigation. (Talk about building a better mousetrap!) Eventually, the system might be able to pick up on subtle things like facial expression.

All of this is not a parlor trick, says Nariyawal, but a sophisticated application of computer vision breakthroughs pioneered by Flutter’s CEO Navneet Dalal.(Nariyawal claims Dalal is the “Tom Brady of computer vision.” His Ph.D thesis has 3,500 citations by other scientists and he's the co-author of "Histogram of Oriented Gradients," which has garnered over 3000 citations. Apparently that’s the academic equivalent of multiple Super Bowl victories.) The science of gesture recognition is the company’s strength and of its seven employees, four have doctorates.

Flutter isn’t the first to envision computers smart enough to interpret gestures, body language and even facial expressions to control a computer. Microsoft’s research division has been doing demos on this stuff for years. But while the Redmond giant is taking (well-deserved) victory laps for its innovative game controller, this small startup is making inroads in actually controlling computers with existing operating systems.

How will Flutter make money? Eventually, says Nariyawala, it will license its technology to app developers who want to integrate this form of control into their products.

That’s one way to go. Another is an acquisition. (Of course, like all founders, Flutter’s leaders insist they’re in it for the long haul.) The most likely candidate would seem to be Apple. But for two years now, the Cupertino giant has been engaged in a contortionist process of migrating the gesture-based interface of its iOS system into the Mac system. There is only so far you can go with using the trackpad as a substitute for the truly intuitive swipes and pinches of a hand on a screen — and none of that works at all when users are several feet away from their gadgets. But that distance seems to be a sweet spot for Flutter.

If Flutter’s claims about the deep technical basis for its performance are true, then Apple should reach into the Cupertino equivalent of Forth Worth for the cash needed to snap up the startup. If that acquisition ever gets a green light, watch for the green lights on millions of Mac webcams to light up — and watch for our computers to start watching us, waiting for the next command.