I'm not a rocker by any stretch of the imagination. But i do love me some Rock Band. Perhaps since i'm a failed wannabe drummer and just a bit of coordination in this game will take you a long way.
I have Rock Band for the Wii, and while I do love it, I am a bit envious of PS3 & Xbox folks that can download tracks and add to their catalog.
One aspect that is the natural evolution of this game is bringing song creation to the masses. Looking at MySpace and what it's done to create a groundswell for music artists, Rockband could be the next big thing. Myspace allowed artists to connect with fans in a much more intimate way. Fans had access to songs pre-release, or web-only songs, artists blogs. Communities were created which inspired loyalty, the artists built their brand on this.
Now picture how fans will feel if they go to their favourite indy artist's site and can download their songs to play along. I think that's something they'd pay for. By putting it on RockBand or Guitar Hero, you're getting what every artist wants : fans to sing and play along over and over again.
That's connecting with your audience on another level.