9p Myungwan Kim's commentary (I much preferred this over the official commentary; he's also commenting tomorrow, so recommend following his stream then, though he might start an hour delayed like he did today).
Fun comment from him: "[AlphaGo] play like a god, a god of Go".
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.