Most maturity models look at SOA in a 'clinical' way and talk about how repeatable and planned the activities to realize the architecture are.
Note
A maturity model is a model that allows executives to review the progress of processes. By having a standard maturity model, it becomes possible to benchmark the SOA levels in your organization. The term maturity relates to the degree of formality and optimization of processes. From ad hoc practices to formally defined steps, to managed result metrics to active optimization of the processes.
While this can be a good way to measure the software maturity in an organization, it does not focus or describe the challenges that are encountered when trying to change something in an organization. As with all change, the organization will hit some hard times during the entire effort.
The most important part is picking the right business process, feature, or service to start with. After that, the follow up needs to be closely guided. A lot...