Yeah, I need to spend some time on 0ad. It's got a bug on our driver currently and I need to get a trace and start trimming that down to a testcase. I don't know how many are playing it currently, but it sure looks like the kind of game I'm interested in, at least :)
One of the things I forgot to mention that's really cool about working with Valve is that, thanks to it being an online service, they collect a lot of metrics. With approval for access, you can get at information like what distribution of chips is in use by valve users, or what share Linux is among their users overall. It's reminded me to give more love to the older chips than I had been, as painful as they are to work on. Things like debian's popcon package are close to this, except it doesn't get active usage information like they do (I've got neverball installed, but I sure don't play it), and each individual distro's popcon equivalent wouldn't be much information on its own.