In-game advertising company IGA and mack-daddy's of PC Gaming id Software are teaming up to bring you Quake Live. The game will run in a web-browser and be playable at a "freemium".
Now, this terrible term, apparently just means that you'll see advertisements in the game.
In addition to Quake gameplay, they are setting up some cool community features like stat tracking and matchmaking.
Full press-release at Kotaku.
