ComputerWorld has a Whitepaper/Pdf available on Software as a Service, Its a good complination of interesting articles on Saas.

Summary as provided by ComputerWorld - The more heavily organizations rely on everyday applications, the less attention they want to pay to them. Rather than paying expensive support staffs to manage complex applications, many customers would just as soon pay an outside organization to buy the software, maintain it, upgrade it, debug it and make sure it's up and running whenever the organization needs it. This concept, once known as the application service provider (ASP) model, has returned and is now called "software as a service."Some interesting Excerpts from the same:
















Source: ComputerWorldPrashanth RaiTag(s):Saas