Some tablet PCs and PDAs even feature an option that allows the screen's content to be viewed right-side up, no matter which way the device is held.

Many laptops sold today include a motion-sensing chip that can detect when the machine is falling, and then automatically protect the data on the hard disk from any damage caused by the fall.

But what BT is trying to do--make an affordable computer that can effectively interface with a user only through moving the machine--is trickier. "The motion-sensing tablet PC is a lovely idea," says Jan Korvink, a MEMS expert at the University of Freiburg, in Germany. "But you'll have to deal first of all with drift."

"Drift" is what happens when microsensors, whether through being continuously overheated or by picking up noise signals, degrade over time. "You have to continuously adjust for drift," Korvink says. "And cheap sensors--the kind you need to mass-produce electronics--tend to drift a lot."

According to Korvink, an even bigger issue is finding the "killer applications" for a motion-sensing PC. That will require, he says, a lot of research into what users might want to employ such a device for, and then tweaking the software to make it extremely user-friendly.

With the Chumby computer, a coffee-cup-size Internet appliance designed to display basic information downloaded from the Internet, users will be able to create their own applications that enlist the computer's built-in accelerometers for input. "The real question is how many Flash developers remember enough of their Newtonian physics to use this sensor effectively," says Chumby software guru Duane Maxwell.

Maxwell also says that the company itself has experimented with writing software that would allow the Chumby device to be used to scroll through RSS feeds just by tilting it.

But BT's Chatting says he is well aware that his work is far from being ready for commercial use. "Just like in the 1970s, [when] we were trying to figure out what we could do with a mouse, there's a lot of learning that needs to be done here." Chatting is hoping to put together a real field trial soon so that he can begin to get feedback on how people might actually use a motion-sensing tablet PC.