I can recommend a recent article at CIO.com, Cloud Computing Calls for Rebuilding Enterprise IT.
The author opens with an interesting anecdote.
I recently talked with the CIO of a large media company who commissioned a study of his legacy apps to determine how many could operate in a cloud environment. The results: 10 percent. That means that 90 percent of those applications will go forward with the same inflexibility and high costs that they've had in the past.
The implications are clear: if you want to fully embrace the cloud, you are going to need to attack those apps that are not currently cloud suitable. Of course, some may never be adaptable to a cloud deployment. And while many may potentially be re-architected for cloud deployment or replaced by SaaS, transformation costs will always have to be weighed against benefits.
Most cloud adoption predictions show SaaS as consuming far and away the largest portion of cloud dollars - not IaaS nor PaaS. The above CIO needs to analyze his applications to determine which are core and which are context. Core activities are those that, from the customer's viewpoint, differentiate the company in the target market (See Geoffrey Moore's Dealing With Darwin website). These core apps are where corporate IP resides and are unlikely to be replaceable with SaaS. At lease we would hope so. Those that are not core are the probable candidates for outsourcing and are increasingly likely to be available via a service model. HP can of course help with this. See Application Transformation to Cloud.