There has been some discussion about an alleged Shigeru Miyamoto interview by GameBrink. In it, Miyamoto apparently says about Wii:
The hardware is basically a GC. We’ve upgraded our development tools to new versions but, you can still use GC programs as they are.
The interview is over a month old. And, according to Joystiq, Miyamoto really said:
The machine is based on GC. We'll be upgrading the development tools, but GameCube code can be used for the most part as is.
Funny how a small syntactical error can make such a big difference semantically.
Sources: GameBrink, Joystiq