The Wii U is to Wii as Wii was to GameCube.
Wii, WiiWare, and Virtual Console games will be supported on Wii U much the same way that GameCube titles were supported on Wii, without any special features or GamePad support.
In an interview with Nintendo of America, they stated that the Virtual Console transfer process was not confirmed to be available at launch, and would require both systems to be present and an SD card. The transfer process works much in the same way the DSi to 3DS process works today.
We will post the full transcript of the interview later this evening.