Daniel Dennett just wrote an article on chess-playing computers and Artificial Intelligence, and a few bloggers are already talking about it. I'm sort of surprised that the concept is getting so much attention. To me, the answer to the question, "does a computer that can play chess demonstrate artificial intelligence" is obvious: it does, but only in a very trivial sense.
Discussions of the methods used by chess-playing computers and how they compare (or don't) to the way(s) that the human brain plays chess are interesting, but I don't really find them all that relevant to the whole "artificial intelligence" discussion. The idea that a single game - hell, a single test of any sort - can adequately assess whether something has "intelligence" is quite simply absurd. The development of a chess-playing computer demonstrates that a computer can be developed that can play chess. That's all.
That's not to say that the development of a chess-playing computer is unimportant or unimpressive. Far from it. Chess has an elegantly simple set of rules that create a game that is anything but simple. Playing chess well requires the ability to see and evaluate an enormous number of possibilities before each move. Developing a computer that can do that was an enormous accomplishment.
But Deep Blue didn't learn how to play chess. It was taught how to play chess. It can do nothing other than play chess. Put a royal flush in front of the thing, and it won't be able to register. It's a machine that has been constructed for a single purpose. It can do that one thing very well, but it can do nothing else.
At least for me, the key to intelligence is the ability to learn. Not the ability to be fed instructions, the ability to learn. The ability to gather information and use that information to develop entirely new skills - without being instructed to do that. My dog can do that - he learned from the cat how to get out a window. A chess- or poker-playing computer can't.
When we get to the point when a computer decides that chess is boring, and holds out for a game of five-card stud instead, I'll start to think about the deeper philosophical questions. Right now, it looks like that's a long way away.