I think it is a bigger deal than chess because it doesn't use brute-force but mostly unsupervised learning. It is not the breakthrough in AGI but it is telling that this approach thoroughly beats all the other Go algorithms (1 out of 500 plays lost, even with handicap 4. And they say that it still improves by training.
I wouldn't say that it's "mostly unsupervised" since a crucial part of their training is done in a traditional supervised fashion on a database of games by professional players.
But it's certainly much more automated than having an hand-coded heuristic.
DeepMind's go AI, called AlphaGo, has beaten the European champion with a score of 5-0. A match against top ranked human, Lee Se-dol, is scheduled for March.