The Mac version of Quake Live will debut on Tuesday, August 18, according to recent comments made by id Software CEO Todd Hollenshead and reported by Macworld last Friday. While the game's web site continues to sport a "Beta" tag, id says in the FAQ hosted there: "We are continuing to make refinements to the game to improve the experience you have and optimize it to support the size of its ever-growing community base."
Quake Live is a browser-based version of id's Quake III Arena, which was released a decade ago. Mac system requirements haven't been announced, but Internet Explorer 7 or 8 and Firefox are required on the Windows side of the fence, so Mac users will likely be restricted to Firefox. The game is free for anyone who registers for an account.