Like the name implies, Rock Band will focus on cooperating with friends as players take lead/bass/rhythm guitars, drums, and vocals and work together to rock out. Guitar, drum, and microphone peripherals will all be available, but you won't need them all at once to play the game. Online play will let players take their favorite instruments and play with friends across the country, a first in the Guitar Hero genre.
Harmonix is working with EMI Music, Hollywood Records, Sony BMG Music, Universal Music Enterprises, and Rhino Entertainment to secure the rights to the ton of hit songs spanning the different rock genres. The music labels also are providing the original master recordings for several songs for use in the game itself. This is a big change from Guitar Hero and Guitar Hero 2, where Harmonix produced new tracks for most of the games' songs.
Rock Band is scheduled to ship for the 2007 holiday season, so you still have several months to wait. Of course, you could use that time to learn how to sing or play guitar or drums and start your own actual rock band. Either way, please don't cover any Fallout Boy.