Awhile back, quite awhile back actually, I was working on bringing one of my songs to Rockband. The process was complex as all fuck but it was a fucking undeniable blast to work on. Microsoft and Harmonix somehow worked out a deal together that allowed independent artists such as myself to release our own music on Rockband with one massive caveat; you had to know what the fuck you were doing. It also is how I initially got into game development. I never ended up releasing the song on the network and not because I failed but to keep this story short, in order for your song to be approved it had to be peer-reviewed. I'm not a big fan of that. Not a fan at all.
Regardless, I'll be at E3 this year and the first question I plan to ask at the Rockband 4 preview party is if they'll be bringing the feature back and how they will go about implementing it this time. Excited and scared at the same time.