"Today we are thrilled to announce that we are bringing Quake Live to Steam. Upon release, players will have the option of porting their Quake Live account to their Steam account, allowing you to play and update the game entirely through the Steam interface."
"... we will launch an update that for the first time in Quake Live's history, will bring about some big gameplay changes. We want to ensure that FPS fans who check out the game on Steam have more fun in their first match than the current gameplay systems allow. We're not talking too much about specific changes yet, especially since the changes need to be taken as one whole package in order to be effective, but we will be iterating internally over the next few weeks to see what works."
Source: http://www.quakelive.com/forum/showthread.php?37332

I'm personally a bit afraid of these possible changes. I hope that they won't break the gameplay balance and the overall feel of the game. Quakelive gameplay is already (almost) perfect, I just can't see how they could improve that by making changes.
But maybe they won't touch the weapons and the physics but rather add an item timer allowed for the players during the game, or stuff like that ?

What do you think ?