Didn't pick up 3, might end up Gameflying it... Rock Band announced over 200 songs to be available for download this year. I am not sure what the GH franchise can do to compete with that. Hardware will improve for both, which is my only issue with Rock Band (the fender sucks).
ONUOsFan is a PS3 guy, so no, the GH guitars do not work with RB
To be fair all around too, Rock Band is currently releasing 3 (not 5-10, thank god, im going through 'MS Points' as it is) songs a week, but with 3 songs/week... 52 weeks... obviously there will be some larger weeks in there to hit 200, and thats cause of the full album downloads. The Who's greatest hits is expected to be the first album released... 'soon'. Nirvana Nevermind and a Metallica album are also comin.