http://icculus.org/twilight/darkplaces/
In the race of the SuperBuild Quakes Dark Places pulls ahead of the competition, rivals Tenebrae (beautifully lit but every thing looks melted)and Telejano (eye candy so gorgeous, a Scag spitting poisonous luggies in your face becomes an aestheticaly pleasing experience) this past week. Lord Havoc released a version on the 18th that if you check through the release notes you'll notice it includes the fact the engine now runs the Quake 3 format -- I tested it in Quake 3 maps for several factors -- Hugeness, model polycounts, patch (curved meshes) rendering, and in all my maps it performed better than Q3 Arena.
BTW, I'm not in any way affiliated with the Dark Places team aside from my plans to release maps specific for the engine in the near future. I don't know the guy, and he does not even bother to answer my e-mails (no offense though, my questions could have very well been stupid ones).