A successful implementation of Business SOA really has to outline and give details about the process of service discovery (business services more specifically) and how an organization goes about outlining the Service architecture map that helps it to zoom in on those services that provide strategic /tactical advantage versus ones that are more utility services and could probably be bought. KPIs around these business services would then help the organization measure the benefits of these business services in the strictest sense in line with its strategies.
So, as I research on SOA, those interesting case studies elude me - however the best source of material I've come across has been from Steve Jones (CTO, CapGemini). In general though, service discovery comes very close to the methodology of discovering domain objects in an enterprise wide system. As Steve has eloquently put - services tend to be around functional nouns, so "Order Management" is a good example, it will have capabilities that are the verbs "newOrder","createDispatch", etc and it will have priorities for its operation e.g. availability, response times, dispatch sizes etc.
It definitely seems like OO design, however this discovery has to be top-down, with business folks heavily involved throughout service discovery. Most organizations struggle with that, but maybe there's light at the end of the tunnel as the industry gets a better understanding and feel for SOA and what such undertakings really require an organization to do.