Wow, 1 million servers across all of their datacenters. I wish I could visit such an operation just to get a sense of the scale. And how do you exactly manage that much compute/storage capacity? Amazing.
Clive, this should've been the first comment I got, not all this :(
I guess the answer to your question is this - http://msdn.microsoft.com/en-us/library/bb895144.aspx