It's amazing how many of these are popping up. I'm loving it since arena shooters are one of my favorite genres. The Blitz boards have quite a few of these in production.
Grid Wars is the farthest along and it's a ton of fun. If you've been itching for GW2 but you can't find a 360 give this game a shot. It's not a final version but it's very playable.
http://www.blitzbasic.com/Community/pos ... opic=55273