One of the barriers to full realization of SOA potential is shortage of critical skill sets needed to successfully implement SOA initiatives. Let's be honest about the reality of the situation. Development teams typically are made up of outsourcing partners, temporary consultants, and employees. They all have varying degrees of training, skills and motivations when it comes to delivering a solution. These teams are responsible for carrying out the vision, approaches and processes laid out by the EA team. In general, the EA teams do a good job of laying out the target architecture, governance processes, best practice etc. However, the developer community is generally focused on getting things working in the shortest time possible with little regard to making sure the services have the right level of de-coupling and are designed and developed correctly for future re-use.
Having a strong governance structure can help relying too much on governance leads to a situation where the governance body itself becomes more of a micromanager than an oversight entity.
In my opinion, the right team structure is when at least a few key members (preferably in permanent capacity) have the leadership and communication skills and have full understanding and appreciation of SOA. These members can act as mentor and provide the necessary oversight to make sure services are delivering on the promise of business agility.