Tanks in the cloud – Computing services are both bigger and smaller than assumed: “Clouds bear little resemblance to tanks, particularly when the clouds are of the digital kind. But statistical methods used to count tanks in the second world war may help to answer a question that is on the mind of many technology watchers: How big is the computing cloud? This is not just a question for geeks. Computing clouds—essentially digital-service factories—are the first truly global utility, accessible from all corners of the planet. They are among the world’s biggest energy hogs and thus account for a lot of carbon dioxide emissions. More happily, they allow firms in developing countries to leapfrog traditional information technology (IT) and benefit from advanced computing services without having to build expensive infrastructure… The “cloud of clouds” has three distinct layers. The outer one, called “software as a service” (SaaS, pronounced sarse), includes web-based applications such as Gmail, Google’s e-mail service, and Salesforce.com, which helps firms keep track of their customers. This layer is by far the easiest to gauge. Many SaaS firms have been around for some time and only offer such services. In a new study Forrester Research, a consultancy, estimates that these services generated sales of $11.7 billion in 2010.”