With virtualization fuelling the growth of cloud ,the new slogan is that no one gets fired for buying VMWare (the leading virtualization vendor) makes a lot of sense. Though In reality virtualization brings its own set of challenges such as VM sprawl, added complexity, security issues etc.
We can think of Virtualization as the bedrock of cloud computing .Essentially it enables the massive pooling of commodity IT resources in data centers of the large cloud service providers - a case of economies of scale in technology environment. The efficiency gain thus obtained is then passed on to consumers who then avail of these computing resources at much lower per unit costs. Also users only consume and pay for the resources they ask for and as they release them, it is returned to the common pool - reusability is another layer of efficiency as compared to traditional IT setups.