Activision have recently been quoted in interviews with Edge magazine and also statements online in saying they would like the Guitar Hero series of games to become a mainstream way of listening/interacting with music, and they plan to strengthen this by making an iTunes style store of the multitracks needed to play the game. They have had digital download extras for the game in the past, but this time it's planned on a big scale, talking to labels for full catalogue downloads and the like...

Will be interesting, to say the least!