These song-programming tools have been available for a while now, but tonight an open beta testing period will begin. Creators and bands will have a chance to share their songs with a community of critics and fans. Once the library is big enough and the bugs have been exterminated, the content will go live on the average player's Xbox 360 or PlayStation 3 Rock Band Network store.
Up to this point, Harmonix has had to create each Rock Band track itself. It can only crank out a few songs per day, and these songs basically print money, so why not source this stuff to the users? Bands can team up with talented track-makers working out of their basements (or the band members can do it themselves if they're savvy), then make a profit and gain exposure through the store, which will give them a 30% cut.