A fairly detailed Doom 3 preview has been posted on Telefragged, based on (you guessed it!) the QuakeCon presentation. It provides some unique insights into the monsters and weapons, however.
The monsters were all very well done, and while there aren't too many of them, there are plenty of new types to come. Currently, there are both skinny and fat zombies, a new type of Imp that throws fireballs and also will leap at you with an attack if you're close, and then there are the huge dog-like monstrosities (which seem to be a successor to the Pink Demon). Finally, Tim Willits' separate demonstration of the game showed off a monster they just put in, which was the Revenant from DOOM II. He still has the shoulder-mounted rocket launchers, and he of course shoots the floor near you to make sure you eat the splash damage.
Sweet Christmas, the Revenant is back.