Considering the certification process through the PS3, payments, and legal wrangling that will likely need to occur (which as I understand is all handled through XNA for the 360), I have a distinct feeling there are going to be a lot of really pissed off PS3 users when RBN only adds a few songs per WEEK to our DLC offers.
And my biggest concern there is that one of these days a really obscure band that I like is actually going to sign up and release content that never makes it to PS3. I can handle timed exclusivity, delays, and waiting, but I don't much like the idea of never having access.
I still love my PS3, but considering I upgraded to a next-gen console just before RB1's release for the sole purpose of having easy access to as much DLC as possible, this RBN thing is almost certainly going to turn into a giant kick in the nuts. And, as of the RBN announcement I already had a 500+ song library... so it was WAY to late to go out and restart on a 360.