My daily routine is to answer e-mail from somebody, somewhere, asking me why his SOA doesn't scale. Unfortunately, the answer is something these people don't want to hear. It's really the fact that they took the wrong approach, used the wrong technology, and the fix is going to be painful. However, you can avoid these issues just by doing some additional planning and testing upfront before you commit to a solution.
The core issue is that many SOA technology vendors haven't focused on scalability in their solutions. Instead, feature/function enhancements are the rule of the day. It's more important to add orchestration features and more adapters to your solution than to figure out how to pump more information, and manage more services. So these single-threaded solutions, on top of the issues around Web Services in general, make for solutions that are more about integration than true business transaction loads. Not to mention supporting the notion of both reuse and agility.
