Just picked up Caverns of Socrates by Dennis L. McKiernan. It's pretty awesome so far- basically, a bunch of folks developed an AI computer that they are testing by taking a known, award winning MMORPG team and sticking them in a Virtual Reality of the universe they played- the people become the characters they used to role play. It's pretty deep in terms of discussions about the brain, neural functions, sentience, consciense, and morality and it is EXTREMELY well written!
Jeff