It's worth noting that the match is under Chinese rules and not the more popular Japanese style rules (Korean rules are also Japanese style). That's because Chinese rules are easier for computers.
It would be interesting to have another match played on Japanese style rules.
There have been a couple of brief discussions of this in the Open Thread, but it seems likely to generate more so here's a place for it.
The original paper in Nature about AlphaGo.
Google Asia Pacific blog, where results will be posted. DeepMind's YouTube channel, where the games are being live-streamed.
Discussion on Hacker News after AlphaGo's win of the first game.