CNET News has posted a story about how Google manages their server farm(s). This once secret information reveals a company who, despite their revenue, is looking after all the pennies and trying to do so in a way that helps the environment as well.
They design their own servers and use 12v DC power supplies with power conversion on the motherboard so no AC to DC conversion is necessary on the server itself. To top that off, no UPS is involved; each server has its own 12v battery attached to it for backup power purposes.
Everything is housed in standard shipping containers (like those you see on cargo ships) which can be moved quite easily if necessary. [This is not unique to Google but perhaps it was when they started doing it in 2005.]
Quite clever actually. And, very efficient.
Full story here: http://news.cnet.com/8301-1001_3-10209580-92.html
Added: And here is a link to the original designs used to test the search methods…