Google bought DeepMind for, reportedly, more than $500 million. Other than possibly Eliezer, MIRI probably doesn't have the capacity to employ people that the market places such a high value on.
I'm not saying MIRI should've hired Shane Legg. It was more of a learning opportunity.
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.