One of the coolest features that the iPhone possesses is the ability to flip a photographic image based on the position of the handset. This is not new to the gadgetry world. We are all accustomed to similar features on our video cameras. However, the iPhone goes step further, and is not only capable of flipping images on the screen, but can also resize them according to screen ratio.
An accelerometer is a built-in device that can measure the acceleration of a camera or similar device. As you may already guessed, an accelerometer uses the gravitation of the earth to figure out its own position, as well as the position of the device that it is a part of. Probably the most recent and popular application of the accelerometer is the Wii Remote.
Not only is the accelerometer used to control screen flipping in the iPhone -- it has far greater potential as a device to help play downloaded games with the iPhone. Software companies are creating games for phones with accelerometers, games with names like Tux Racer and Neverball.
It is interesting to note that most modern accelerometer measure only X and Y acceleration components. Always innovative, the engineers at Apple have equipped their accelerometers to measure and expose X, Y, and Z (or vertical) acceleration components, making it possible to implement such features as "jump when I jump”. The possibilities for using this feature in game design are virtually endless, and are certain to make the iPhone a hit with many gamers accustomed to playing with handheld devices such as the Sony PSP Handheld Entertainment System
Accelerometer technology is not new to Apple and its product line. The first known use of the accelerometer by Apple was in the iPod nano device. Apple produced The Sport Kit2 that allowed certain Nike shoe models to talk to their iPod nano. A sensor was used to measure the activity of the person wearing the shoe, and then wirelessly transfer data to the device. With this in mind, one can see that the iPhone is certainly not a testing ground for accelerometer technology.