Rocky Lhotka opines about SOA.
I want to add a related link to this discussion. SOA is an architecture to solve a problem that has been around a long time. That problem is getting disparate applications to talk to each other. This problem crops up all time, especially for companies that fall into the Fortune 500, 1000, etc. categories.
Rocky makes the point that SOA is dealing with trust boundaries. Roger Sessions has been preaching this philosophy for quite a while now. Roger doesn’t use the term “SOA”. Instead, he uses the term “Software Fortresses”. I think Software Fortresses are the end, and SOA is the means. Roger publishes a newsletter, and he discusses SOA here and here