Even today, Google is serious about exerting total control over the servers in their now-massive server farms. They build their own high-efficiency power supplies, and conduct fascinating, public research on disk failure. Current estimates put Google's server farm at around 450,000 machines - and they're still custom built, commodity-class x86 PCs, just like they were in 1999."
Thats a lot of juice.
(via Google Operating System)