It’s magical! 
Get the same multi-touch gestures like your laptop trackpad – but on your desktop.
When paired with an Apple desktop, it offers the same multi-touch gestures that laptop owners enjoy. Use it to swipe, pinch and scroll. Inertial scrolling on the Magic Trackpad reacts to the pressure and speed you use. The surface is made of wear-resistant glass and, get this: the entire thing is also a giant button, so click away as you would with a mouse.
via tuaw.com
