The good bloodhounds at AppleInsider discovered a patent application
filed for Apple in June 2009, that details a new touch-sensitive, user interface designed for tablets. Signs of Apple's tablet UI first appeared Apple's tablet UI in early 2008. The document details a hand-based system that would allow "unprecedented integration of typing, resting, pointing, scrolling, 3D manipulation, and handwriting into a versatile, ergonomic computer input device." It's a good read.