Activision just put out a new trailer for Quake 4.
There is a brief description of the trailer, plus links to the downloads at http://www.game-instructions.com/news/quake-4-trailer/ (sorry, kinda a cheap plug. But, if you don't want to download the sucker, you can at least read about it and check out some screenshots.)
To save you some linking around time though, the downloads are available from 3D Gamers (http://www.3dgamers.com/news/more/1096481842/)