Well the thrustmaster never came out until the Wii came out. I believe its "compatible with Gamecube games when used on the Wii" because its a Wii accessory not a gamecube accessory.
Here's a link to circuit city which sells them in store. http://www.circuitcity.com/ssm/Thrustmaster-for-Wii-663296412447/sem/rpsm/oid/203191/catOid/-16761/rpem/ccd/productDetail.do
If you read the description it states that the controller is compatible with gamecube games and some wii games. It...
I just bought a couple of the pelican G3 PL-7008 off of ebay and they are supposed to be just as good if not better than the wavebird from what I have read, plus they have rumble. If you are going to search for these on ebay don't type in the brand or model number cause the people selling them...