CVG has it on sound authority that the game has now been in development for at least six months under the guidance of a different team, although the identity of the third party is unknown at the present time. In addition, there is even talk of the game leading on Xbox: John Carmack has been part of the Xbox advisory commission in the States since the formation of the body.

Carmack has mentioned a few times that it's almost a certainty that DOOM technology (most likely the tech that would be used for an alleged Quake4) is easily ported to X-Box and would show up on the console. So that is no surprise...