People seem to be approaching SOA more and more as something that is resident in IT only, or even worse is where IT "understands" the business and builds things that are more responsive... without actually getting the business to own or define anything.
If SOA is going to actually make a difference to what is a failing industry then it needs to impact the structural problems, rather than just trying to deliver a new set of technology projects. 80%+ of IT spend is on "business as usual" aka "keeping the lights on" the support and bug fixing of current solutions, paying the maintenance licenses, patching things and generally just keeping them on life support. And then with the 70% or so of new projects that actually fail to deliver what was expected this means...
This means that around 6% of IT spend actually delivers new value to the business. This is fundamentally broken. Therefore if SOA is going to succeed it needs to help more projects succeed, and more importantly either reduce the 80% spend or help deliver more value for that 80%. This means that SOA truly has to be about how you govern and deliver IT, including how you continually deliver IT to the business once it has gone live.This is why I'd argue that SOA isn't even something that gets built, its something that becomes a part of your culture, it changes all aspects of your IT organisation. Otherwise it really just will be yet another techy idea that delivers little or no value down the line.
IT is a broken industry, it takes more than an ESB, some Web Services and changing some design guidelines to fix a problem this large.