Unit testing is one of the essential elements that arose along with the agile design movement. Any self respecting developer now does unit tests, or at least the developer tells the architect that unit tests were done. Clearly, signing a manifesto does not mean a developer knows how to do unit tests correctly. Unit testing may be one of the great cases of lip service, today.
With SOA, unit testing takes on a whole new tenor. Composite applications may always be in flux. The fact that an application integrator is not in charge of all SOA system elements is inescapable. [see Application performance management today, part 3: SOA performance - SearchSoftwareQuality.com]
Related SOA test/performance info
Application performance management today, part 3: SOA performance - SearchSoftwareQuality.com