For your consideration, an article from The Economist
. Perhaps more of an intro-to-cloud than some around here need, but it includes the story of how a couple of folks were able to determine the size of (at least part) of Amazon's cloud. It's a cool story that involves German tank manufacturing practices from World War II ... take a look! At one point last year "Amazon’s annual cloud-computing revenues (were estimated)at between $500m and $700m in 2010" but seems those numbers might be low.
Tanks in the cloud - Computing services are both bigger and smaller than assumed
Dec 29th 2010