http://www.gameinformer.com/b/news/archive/2011/06/03/confirmed-touchscreen-portability-of-next-nintendo-controller.aspx
It's about as official as official gets: Nintendo's next console will have a six-inch touchscreen and be a portable console by itself.
In addition to those details, Nikkei (subscription required) also reports that the controller will have a camera that players can use to import images to create characters in-game with. The publication speculates that the console could come out in mid-2012 at the earliest.
Nintendo's E3 press conference will be streaming live here at gameinformer.com as soon as it gets rolling on Tuesday morning. Expect the official word then.