I don't believe Houshalter was referring to proving Friendliness (or something along those lines); my impression is that he was talking about implementing an AI, in which case neural networks, while "scruffy", should be considered a legitimate approach. (Of course, the "scruffiness" of NN's could very well affect certain aspects of Friendliness research; my relatively uninformed impression is that it's very difficult to prove results about NN's.)
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.