In a GameSpot article about the launch of DOOM 3 Xbox and DOOM 3: Resurrection of Evil, id Software CEO Todd Hollenshead talks about a few id related topics before mentioning this about QuakeCon: "We'll have Quake IV multiplayer to play". That should convince some people to attend. Meanwhile here's a bit about id's plans for console support

Addressing whether future id titles will be written for PCs or consoles, Hollenshead took a pragmatic approach: "Well, that's really more of a financial question than anything else," he said. "Over the past few years, PC game sales have either declined a little bit or stayed relatively flat, while console game sales have seen mostly double-digit growth. I don't know if we'll be releasing multiple SKUs at the same time, but as for PS3 and Xbox 2 and so on, yes, we will continue our development effort on the consoles." "John [Carmack] has been playing with the tech on the new consoles for a bit now," he added. "I obviously can't talk about that as it's all under [wraps], but I think developing for multiple consoles will happen at id."