This is a pretty good article introducing the concept of Service-Oriented Architecture. As with all buzzword related to IT, the following caveats are true:
- It is a new way of looking at things.
- It is not a new way, just a evolution of current thinking.
The Truth About SOA - CIO is a good opinion piece by Christopher Koch about SOA. Koch is a writer for CIO with a good mix of optimism and scepticism regarding new technology.