From Nintendo.com:

Launches:
2012

Size:
Approximately 1.8 inches tall, 6.8 inches wide and 10.5 inches long.

New Controller:
The new controller incorporates a 6.2-inch, 16:9 touch screen and traditional button controls, including two analog Circle Pads. This combination removes the traditional barriers between games, players and the TV by creating a second window into the video game world. The rechargeable controller includes a Power button, Home button, +Control Pad, A/B/X/Y buttons, L/R buttons and ZL/ZR buttons. It includes a built-in accelerometer and gyroscope, rumble feature, camera, a microphone, stereo speakers, a sensor strip and a stylus.

Other Controls:
Up to four Wii Remote (or Wii Remote Plus) controllers can be connected at once. The new console supports all Wii™ controllers and input devices, including the Nunchuk controller, Classic Controller, Classic Controller Pro and Wii Balance Board.

Media:
A single self-loading media bay will play 12-centimeter proprietary high-density optical discs for the new console, as well as 12-centimeter Wii optical discs.

Video Output:
Supports 1080p, 1080i, 720p, 480p and 480i. Compatible cables include HDMI, component, S-video and composite.

Audio Output:
Uses AV Multi Out connector. Six-channel PCM linear output through HDMI.

Storage: The console will have internal flash memory, as well as the option to expand its memory using either an SD memory card or an external USB hard disk drive.

CPU:
IBM Power-based multi-core microprocessor.

Other: Four USB 2.0 connector slots are included. The new console is backward compatible with Wii games and Wii accessories.