Neural networks may very well turn out to be the easiest way to create a general intelligence, but whether they're the easiest way to create a friendly general intelligence is another question altogether.
They may be used to create complex but boring part of the real AI like image recognition. DeepMind is no where near to NN, it combines several architectures. So NNs are like ToolAIs inside large AI system: they do a lot of work but on low level.
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.