A lot of rumors floating around. According to Wikipedia, people can't even agree on what the controller is. http://en.wikipedia.org/wiki/Project_Café Here's a whole article on Gameinformer about it. http://www.gameinformer.com/b/news/archive/2011/04/14/new-nintendo-console-at-e3.aspx
There's also a 3 page thread on here about it. http://www.thephins.com/forums/showthread.php?61039-Nintendo-working-on-new-console