Here is one Nintendo employe thoughts on it.
LinkWe still don’t know if you can play Wii games in the Wii U GamePad. It’s not confirmed, we don’t have any information yet, but as you say (speaking to the interviewer) Wii U is… you can play old Wii games, and as you also said, the Sensor Bar is included in the Wii U GamePad, so you are able to point the Wii Remote at the Wii U GamePad. It makes sense, but we have no information or confirmation about this feature.Being able to play Wii titles on the GamePad would be pretty darn neat. Though, I can imagine it’d be odd controlling some of the console’s titles…
If they do add such a feature, I can see 2 people playing 2 different wii games on one system.