It's not just enough to model your IT as reusable services, you need to model your business that way as well.
This is the topic of an upcoming IBM Webcast, "My CEO thought Flexibility & SOA were just an IT issue until I told him this...," which will run on Tuesday, April 10, 2007, at 10:00 AM PT / 1:00 PM ET / 6:00 PM GMT. The speaker is Sandy Carter, IBM's Vice President of SOA & WebSphere Marketing, Strategy, and Channels. Another speaker will be the CFO of Delaware Electric Cooperative; see SOA Success at Delaware Electric.
Also check out Sandy's new book, The New Language of Business. If you register, you'll get access to this sample book chapter: "Chapter 11: Putting It All Together."
With SOA, we tell IT to align themselves with the business. Two problems I've heard about are: the business doesn't know what it wants, and the business (seemingly) does things in such a disordered fashion that it's impossible to model as reusable software components. To get past this, the business needs to explicitly perform its operations as reusable components and communicate that model to IT so that they can develop software to automate and support these components.
SOA, it's not just for IT anymore. Business has to get involved too. If your business execs need to get this message, send them to this webcast.
For a list of current and past webcasts on SOA, check out Service Oriented Architecture (SOA) Webcasts.