Synergy is a well known open-source project that allows you to share a single mouse and keyboard across multiple computers, each with its own screen and hardware. You just move the mouse around and switch keyboard from device to device. I think it best represents Ive’s and Jobs’ definition of “magical”, actually.
By the way, there’s an iPad version coming out soon. Developed by Matthias Ringwald, this version will rely on BTstack - a popular hack that brings proper Bluetooth Stack to iOS device through jailbreak.
The video embedded below shows a preliminary build of BTstack Synergy, which already lets you move your mouse to the iPad screen and select icons and menus with it. Keyboard support is on its way, too, says the developer. We’ll keep you posted about this as soon as a stable version shows up on Cydia.