There is a great article available on Gamesutra on current trends and the future of Game AI, going into specifics on what types of AI some companies use to develop their games and what types of AI will be used more in the future, with a focus on the move to what is called A-Life:

For example, when a hungry character walks near a refrigerator, the refrigerator's "I have food" broadcast allows the character to decide to get some food from it. The food itself broadcasts that it needs cooking, and the microwave broadcasts that it can cook food. Thus the character is guided from action to action realistically, driven only by simple, object-level programming.

If you are a gamer that really appreciates a game with good AI this is a must read, its intresting to note that AOK get a mention for its Terrain Analysis. Check out the full deal here

AoK's terrain analysis helped, but it still decides to go the wrong way around bushes occasionally.

Seems learning Ai's have been given the flick too, can't understand that ..