The developer's home will be Alliance on Broxigar (PvE), however the Patch 3.1.2 PTR servers are all linked together for PvP Arenas and Battlegrounds, so you'll be able to face them no matter where you are.
We've previously covered some of these events, and you can see results in our gallery below. There is no word if the infamous Ghostcrawler will be making an appearance. But I suggest all you disgruntled <insert your class here> show up and hope for the best. After all, he promised you a pony and you didn't get it.