sorry...i posted this on my blog and forgot to post it here 
yes....i actually played Rock Band yesterday on my college campus of Georgia State. A group sponsored by MTV was there with a trailer with about four sets for demo group play. Also, they had a big stage for people to play and be recorded that would be sent to MTV.
Ya'll that game is amazing! The thing that makes it so great is of course its multi-player options. Even though it was only a demo, the music selections were great. Songs by Black Sabbath (Paradise), Jet (Do You Want to be my Girl), Nirvana (sorry I can't remember the name), Stone Temple Pilots (Vasoline), and sooo many more. About 20 songs in all. I got the chance to play guitar and sing. The guitars that come with the game are similar to the ones for guitar hero. However instead of colorful buttons that you can see, they only have colored indicators on the edge of the guitar that look like this:
__________________________________________(side of guitar)
------------- ---------------- ---------------- ------------- (colored lines)
There are 10 buttons in all. One set of five at the top most part for regular guitar play. And the other set closer to the bottom for bass play. You can play either top or bottom for bass guitar though.
The song feature is pretty much like any type of karaoke video game you can imagine. Stay on pitch and chime in at the right moment and you'll be fine.
The drums though I didn't get to play, I can tell are tricky. If you won't have rhythm, you may want to practice on your own.
The cost of this entire set is about $180. But one of the guys there I spoke with said that its pretty much sold out until February...