I had heard about this a while back before the beta was opened, but just recently after NightrainSrt4's "What have you beaten..." thread I noticed he had it listed. I figured I would take a look and WOW, its fun as hell! I had played Quake III Arena quite a bit back when it came out, but as most games go it faded due to newer better looking games. Its been fun playing it online again, and the best thing is its FREE and you play it from a browser. It downloads a small plugin, and it can be played fullscreen.
If you decide to check in out, my profile is OvRiDe, with a TBCS clan tag
http://www.quakelive.com