An interesting quote from a ZDNet article:

IBM’s consulting-driven approach to services-oriented architecture reflects the company’s belief that SOAs represent a significant shift in computing systems designs, said Ron Schmelzer, an analyst at research company ZapThink. Much like earlier shifts to client/server and Web-based computing, SOAs require companies to rework how they design, build and run their business applications.

I thoroughly agree — SOA is not something that you can buy in a product, whatever flavor of ESB, Fabric, or Integration Infrastructure that product may provide. SOA is as much an architecture of your business, and an architecture of your development process, as an influence on technical implementation.