Yesterday I attended an IBM presentation by VP Doug Cox on Service-Oriented Architecture. The pitch was very much around what are the value-adds WebSphere can offer to leverage an SOA. I've been to some other vendors pitches recently including BEA's, but Doug's approach struck me as a very clever sales technique. There's a lot of effort that goes into explaining what is SOA, but that's not really where vendors should focus their efforts. Consider that the vendor-neutral aspects of SOA mean that vendors will gain their competitive advantage not from their SOA support, which is (will be) ubiquitous, but instead on their value-added use of SOA.
IT executives still need to understand SOA, so perhaps it's not so bad that they should seek their definition from elsewhere. I'm about halfway through professor Thomas Erl's Service-Oriented Architecture: Concepts, Technology, and Design (ISBN 0-13-185858-0), which is a thick one that provides a good framework for explaining the architectural concepts and implementation strategy is sufficient detail.