First, what is XaaS? Is this just more marketing fluff? Why do we need to define yet another model to fully describe cloud services? I contest that XaaS is a legitimate term, and that it is useful to describe a new type of cloud services — those that make use of IaaS, PaaS, and SaaS all neatly delivered in one package. Such packages are intended to fully displace the delivery of a commodity IT service. My favorite example of XaaS is desktop as a service, or DaaS.