I actually work with Jim Gao. His design doc was already open in another tab when I saw this article. Jim's a really smart guy. Really nice guy too.
I can't talk too much about it. You have a huge amount of electricity coming into the DC, on the order of a lightning bolt, and it has to be intelligently choreographed to make the best use of it. Then you have to carry away the heat. There is a lot of machinery to do that, and by accurately predicting where and when power is going to be needed, both for servers and for cooling, you can allocate your resource (chillers, transformers, fans, etc...) most efficiently. It's complex. It involves weather patterns and coolant flow rates and even minor things, like when the heaters turn on to keep the oil in the generators at the right viscosity in case of an emergency. You need to know all that stuff to decide where to best route (provision) the power. If you statically allocate power to cooling and other subservient systems, you lose the opportunity cost to use that power for more server machines. The more intelligently you can control things in real time, the more efficient you can be.
The coolest part is Jim had a clever idea, wrote it up, and it became reality based on its own merits. Jim is relatively new and junior at Google, but that didn't matter at all.