Software as a service has come far in a few years, adding new functionality and depth. In time, users will move beyond SaaS to "cloud computing," the delivery of IT and business functionality in a utility environment. Cloud computing encompasses on-demand infrastructure (compute, storage, networking), and on-demand software (operating systems, applications, middleware, management and development tools), customized dynamically to fit immediate business process requirements, along with the ability to deliver and manage those business processes.
Source: News Factor, http://www.newsfactor.com