GameSpot has posted their own Doom III Preview, which centers around an interview with the game's lead designer Tim Willits. This particular preview does not carry a mere regurgitation of known information like so many have before it; for example, here Willits comments on the multiplayer aspect:
Doom III multiplayer is incredibly intense, and the light and shadows play a much bigger role in the gameplay. Never before in a multiplayer game have players had to worry about their shadow and whether or not it has revealed their position, or been able to shoot out lights so they can hide in the darkness. This alone adds a level of reality, depth, and atmosphere that is again going to redefine expectations about how a multiplayer game should look and feel.
There's quite a bit more interesting information, including a new screenshot, so go read it already. Thanks to Opulent for pointing this out to us.