I just recently bought a new PowerBook. One of the new features Apple stuck in these new beasts is what they are calling AMS – the Apple Motion Sensor. Basically it appears to be some sort of accelerometer that can measure sudden changes in movement and automagically park the hard drive heads before something bad happens (like hitting the floor.)
However, it appears that it can also measure the attitude of your machine. That is, it can tell how “tilted” a machine is in all three axes. It uses this to unpark the heads when the machine returns to being level. It also can be used to do some really cool stuff, as this web site demonstrates. On this page, Amit Singh gives us some programs that retrieve the sensor values and do some cool things.
One is a small window with an OpenGL-rendered PB that rotates in conjunction with you’re rotating the physical machine. Very, very cool stuff. Another is a bicycle wheel in a window. When the PB tilts, the window itself rotates to keep it level relative to your (physical) desktop. If you have one of these new PowerBooks, download the samples – there is some cool stuff there to show your friends.