Nintendo has filed a patent for an accessory that gives touchpad functionality to the Wii remote. The device uses a combination of LED and mirrors to imitate the effects of a touch pad, though it doesn't seem to able to project images directly onto the screen like you would see in the DS or Wii U. The patent states it could be used for drawing applications or to add a mouse pointer interface to a game.
Siliconera reports that the device would snap onto the Wii remote, but as long as your fingers aren't touching the pad it would still react like a normal controller.
The Wii U will include one of its new touch screen controllers, and all of the demos we saw at E3 involved only one person holding it while the other players used Wii remotes. Nintendo has offered conflicting statements on multi-controller support for the Wii U, and a solution like this would offer some of the functionality for each of the players. Nintendo has also hinted that the 3DS could potentially double as a Wii U controller, but has seemed hesitant to commit to the idea.
Companies patent all kinds of ideas, but not all make their way to market. It will be interesting to see if this patent will ever come into fruition.