Quake Live is a free, browser-based, multiplayer-only version of the popular first-person shooter, and it's Windows-only at the moment and packed -- I've tried to play, but have been locked out by thousands of people ahead of me in server queues. Even some of the developers at id are having issues. One of them (a Mac user, apparently) complains that even he has to jump into Boot Camp just to play his own game.
A little more significantly, Carmack says he recognizes that while there are lots of other choices for PC gamers, a game like Quake Live could make a much bigger splash on Mac and Linux, where there aren't as many other developers and titles grabbing for attention. We've heard that before -- while developers claim there's not a big enough base for them on OS X and Linux, the truth is that some of your best and most loyal customers will use Macs.
Good to see that Carmack recognizes there's an audience here who want to shoot each other online, too. Hopefully we'll see Quake Live running on our machines sooner rather than later.