I ran across an interesting article that compares the largest of the botnets — the Conficker botnet — with the largest web application providers and the size of their infrastructure. The article uses the term “cloud” in a way that I don’t necessarily agree with, since they use it to describe the overall size of a company’s infrastructure (e.g. according to the article, Google has 500,000 servers) rather than the size of that company’s infrastructure that is available for use as part of a genuine cloud-based service. But, overall, the article does illuminate the fact that botnets have an architecture that is very similar to that of cloud-based service providers, leveraging a virtual datacenter comprised of compromised hardware around the globe. And the sheer size of the Conficker botnet, which, according the article, is over ten times the size of the largest web application provider, would make it, by far, the largest cloud provider in the world by an order of magnitude.
The article can be found here: http://www.networkworld.com/community/node/58829
This article is also noteworthy, I think, because it includes some sizing data for the largest players in the industry. If true, this data represents one of the first genuine, accurate comparisons of the infrastructure behind the biggest names on the web.