There's an RBR Update on GA-Source where they asked Randy Pitchford about the status of the folks who once staffed the now-defunct Rebel Boat Rocker. His reply reveals the news that they have more-or-less remained together, forming a new company called Gearbox Software:

Most of the RBR content team stayed together. We've re-organized and reincorporated as Gearbox Software.

We're working on a new very exciting project that will be publically announced in just a couple of weeks.