Because Rock Band's existing library just isn't punishing enough, Harmonix will be releasing Rush's epic 2112 as downloadable content for the game over the next week.
The thing here is that, while the song is split into seven "acts", and available as separate tracks accordingly, if you buy the complete song pack you'll get the option to play the entire thing as one song.
And as one song it goes for twenty minutes. You can hear the whole thing above.
Rush's "2112″ Comes to Rock Band! [Rock Band]