Kotaku have managed to search out a bunch of exciting documents regarding Nintendo's Wii U. Among the things they have spied are patents regarding goggle free 3D and HD resolution for the tablet controller.
It also seems like you will be able to connect peripherals, such as light guns and keyboards to the tablet. And while a patent isn't the same thing as a promised feature it is a good hint about the secrets Nintendo may still be keeping as far as Wii U goes.