Some people say that cloud computing is nothing new, a bunch of old ideas and existing technologies repackaged with the latest buzz words. Gartner puts the cloud services market at $46 billion last year, jumping to $56 billion this year and $150 billion by 2013. Call it what you will, that's a remarkable growth projection in the thick of a recession.Why do skeptics continue to doubt that cloud computing is new and different? Because they're partly right--many so-called cloud services are indeed services that we've known by another name. Gartner includes "cloud-based advertising," a.k.a. online advertising, in its definition of cloud services. In fact, cloud-based advertising, at $28 billion, was the single largest area of cloud services (60%) in 2008, according to Gartner.

Nevertheless, other cloud services, including infrastructure-as-a-service and software-as-a-service, are multibillion-dollar markets in their own right. By Gartner's estimate, infrastructure-as-a-service will grow from $2.5 billion in 2008 to $3.2 billion in 2009, and SaaS is about double that with "strong growth." Combined, that puts the infrastructure-as-a-service and SaaS markets in the $10 billion range this year.

Gartner projects that the overall cloud services market will reach $150 billion in 2013, representing a 21% annual growth rate over five years. Gartner VP Ben Pring observes that, given the economy, the growth of many cloud services will be relatively modest over the next two years, but Gartner expects demand to accelerate as business improves and as cloud services "prove themselves."

There's some uncertainty in Gartner's crystal ball. Pring notes that IT trends over the next couple of years are "highly uncertain." And he singles out infrastrastructure-as-a-service as having "the largest range of possible outcomes," which signals that Gartner isn't sure how many developers and IT organizations are going to sign up for Amazon Web Services, Google's App Engine, Microsoft's Azure, and other such services.

With those caveats in mind, the worldwide cloud services market is on track to surpass $56 billion this year, Gartner says. Whether you call it cloud services, hype, or by another name, that's a lot of something, and it's growing fast.