Graeme Devine of idsoftware.com updated his .plan yesterday with reports of Quake 3 and Doom (presumably 3):
Hey.
We will be releasing the Macintosh Quake 3 client hand in hand with the Win32 / Linux clients. We'll also require Mac OS X 10.1 or later for this release.
DOOM is up and running under 10.2, which as an OS is really quite cool (speed is much better than 10.1, although resizing a browser window is still painful).