Well some are rumors on there wiichat members have already dicussed, like the Miis in Animal Crossing. Although I truly doubt that that most of these rumors are true it was still interesting especially this one:
New Miyamoto IP
Miyamoto is working on a new IP on a similar scale to Zelda. It is codenamed ´The Rise of Darkness´.
It is said to be an online-only title, perhaps an MMO. Miyamoto wants every day to be different in the game. An older rumour on the same site pointed to a game that mixed elements of the real world with science fiction and spritual elements, loosely inspired by Buddhism. Gameplay-wise it was described as mixture between Zelda and Shenmue.