There seems to be some confusion about the backwards capabilities of the Wii U. Nintendo originally implied that Gamecube titles will be playable on the Wii U, but it has since backtracked, and the situation is very uncertain at the moment.
"To clarify the capabilities of the Wii U system: As correctly stated, Wii U will not play Nintendo GameCube discs," Nintendo told CVG in a statement. "However, Nintendo has not made any announcements regarding downloadable content."
This is a bit of a PR snafu for Nintendo, and it could turn out to be a pretty big stumbling block if the Wii U has no backwards compatibility for the Gamecube.
Sony faced a similar situation when they announced the PS3 would not support PS2 games, something which many fans are still angry about.