There have been many questions about SOA and cloud computing, so let me be a bit clearer.
While you can certainly leverage cloud computing without practicing SOA, and leverage SOA without leveraging cloud computing, the real value of cloud computing is the ability to identify services, data, and processes that can exist outside of the firewall in SEDC (somebody else's datacenter). Those who attempt to toss things to the clouds without some architectural forethought will find that cloud computing won't provide the value. Indeed, it could knock you back a few steps when considering the risks and cost of migration.
[ InfoWorld's new cloud computing blog seeks to promote a clear-eyed definition so the sustainable cloud can form. ]
There will be some core patterns of success with cloud computing over the forthcoming years. Those who leverage cloud computing within the context of an architecture will succeed, while those who just toss things into the clouds as they think they need to will fail. Remember, SOA provides a great deal of value to cloud computing, and the other way around.
Indeed, one can consider cloud computing the extension of SOA out to cloud-delivered resources, such as storage-as-a-service, data-as-a-service, platform-as-a-service —- you get the idea. The trick is to determine which services, information, and processes are good candidates to reside in the clouds, as well as which cloud services should be abstracted within the existing or emerging SOA.
Not that complex when you get right down to it.