These details are part of a Wii U patent filing. The filing doesn't specifically mean that all details will be included in the final version of the Wii U, but it does mean they are possible.
- Wii U could be outfitted with voice recognition software
- "one or more additional microphones...may be provided on the front and/or back surfaces"
- facial recognition
- controller may be able to recognize facial features
- can be used as a videophone by "exchanging images and sound"
- peripheral examples: "a game-specific controller (gun-shaped controller, etc.) or an input device such as a keyboard"
- "might" feature a 3D display on the Wii U controller
- "might" feature a HD display on the Wii U controller
Source