We've seen the 360 and the PS3 announcements that the instruments will be compatible with both games (and rock revolution as well) but to my knowledge Nintendo hasn't made any such announcement. Do you think that Nintendo will? Or, if they already have made that announcement could someone please tell me or provide a link? That'd be great.

Hmm..I'm guessing that the Wii won't be any different from the other versions in terms of compatibility. I've got no proof however, it just would seem weird if it were different. You could probably post this question directly to the official RB forums and get a response from a developer.

so that would be a "nothing confirmed" then?

I've asked this question of the bombcast crew but it wasn't answered =/

I am planning on getting the GH bundle, and then buying the RB game disc...but Im still not sure if everything will be compatible with everything....

I've read on the GH forums that they will NOT be compatible.  The Activision / VV instruments use the Wii-mote to communicate with the Wii whereas the RB instruments use Bluetooth to bypass the wii-motes.  That wasn't an official quote, but it made sense to me.  I'm sad if that's the case, b/c there are some great songs on the RB discs that I would love to play, but the music creator and more realistic drums have me sold 100% on GH WT if I have to pick only one. =/

I see no reason for the instruments to be incompatible. There is almost no excuse except for lazyness/pigheadedness by the developers on both sides. The instruments are transmitting a signal to the Wii everytime a note is pressed or hit. It shouldn't matter that the methods by which these signals get to the Wii are different. As long as each developer knows what these signals are going to be they should be able to code the game to recognize the other games instruments. Again I see no real technical limitation. It will come down to the developers reaching out to one another and taking the time to do it right.