There has already been some hype about the audio interview between Hub Vandervoort, CTO, Progress Software, and an industry expert from Gartner, but in case you haven't listened, listen to it.
During the interview, Hub discusses how companies that are working in federated environments need to approach the governance of their SOAs in both run-time and design-time contexts. If you listen, you might gain important insights into how to isolate and manage multiple SOA domains, determine which aspects of your SOA you should control at the edge, the importance of semantic control, and how event-driven ESBs can ensure loose coupling between SOA stacks.
Download the audio file entitled, Multiple ESBs: SOA Reality in a Federated Environment .