A report on the website of the generally reliable Nikkei newspaper has supposedly confirmed rumours of a six-inch integrated touch screen for the controller of the Wii's successor, currently only known as Project Cafe.
The report, translated by Andriasang, says that the screen will be used for supplementary controls for games, but could also serve as a separate portable device independently of the console.
The controller allegedly features a rechargeable battery and a camera, which could be used to add photos to Miis or other in-game avatars. Nikkei's report doesn't give the final name, price or definite release date for the hardware, but does suggest a possible release window of "mid 2012."
For some professional speculation on the possible capabilities of Nintendo's new machine, read Digital Foundry's piece on the hardware's potential.