I blogged about how we upgrade a live data center over on the Server Fault blog, which you may find interesting. It details how we planned and executed a large hardware refresh in the Stack Exchange New Jersey data center complete with hundreds of photos along the way. I love our hardware upgrade trips and will try my best to share future ones the same way. Expect a similar post on building the Denver data center around June this year.
If reading isn’t your thing and you want to go directly to the server porn, never fear. The album of the move (fully commented) is here: http://imgur.com/a/X1HoY