Service oriented architecture is not a thing that you do, and it definitely isn't a thing that you buy. But it is something tangible, a style if you will, just as Roman, Greek or Modern are styles of architecture.
Why the fussing about semantics? This was a key point discussed over and over again by members of the SOA Manifesto Working Group, and an issue that is endlessly creating confusion in the market. In fact, it's a semantic slip that even members of the group had to work at to keep in check.
There have been some comments raised about the Manifesto's preamble, which said the following:
"Service orientation is a paradigm that frames what you do. Service-oriented architecture (SOA) is a type of architecture that results from applying service orientation."
Yes this opening statement may seem like a statement of the blindingly obvious, like "the sky is blue" or "the ocean is wet" or "Hollywood makes crappy movies" or something like that. But there was a lot of discussion around this statement, and the intent was to dispel the notion that SOA is this thing that you do or can buy. In fact, vendors and consultants have been abusing these semantics and milking millions from customers with this notion for years.
That makes as much sense as the Romans going out and buying their architecture. It was important to put this notion to rest (definitely no pun intended) once and for all, and it was felt by the group that this was such an important statement that it was elevated from originally being a principle to the preamble to the entire document. And "applying service orientation" is the action that goes into building an SOA-enabled infrastructure.