Guitar Hero and Rock Band video game songs as backing tracks?

[Number Of The Priest]

I've only had brief experience dicking around with this game at Wal-Mart. Is there a way to export the tracks, sans-guitar (or at least sans-rhythm-guitar), to MP3 format, so that we can play over them? The "master tracks" from the real bands intrigue me.

I did a search on Google and didn't find any kind of download site. I'm honestly surprised this hasn't been started yet. (This is your cue to start ripping the songs. )