Stomped has posted an interview with Jan Paul van Waveren aka "MrElusive," the contract AI programmer for id Software. Most of the interview talks about Q3A but there's a little bit of Doom stuff in there too:
Stomped: Is it safe to say you are doing some work on the new Doom game?So there's going to be scripted sequences in the single-player game, and the enemies will have different personalities... *takes notes*
van Waveren: I'll be doing some stuff with it. I think I will probably be working with Jim Dose, either working on the scripting or together with him doing the AI for Doom. I'll just be helping out there.
Stomped: What's the challenge in creating the AI for a single-player game as opposed to a multiplayer game?
van Waveren: I think the variety of enemies you have. You probably want to share certain things with all the monsters, because you want to share code and information for all the enemies. At the same time, you want to make them versatile and different enough so they become different characters with different personalities.