Services inside an application

My post on the risks to WS success drew a comment from Tom, who felt that what I said was a little misleading. Specifically, he said:

I think your point about SO in internal pieces of a system is a little misleading. It can be a good idea. I have designed a system that compartmentalizes some areas as services. For example, an investment service to retrieve fund information. This can then be used by the next development, but avoids the old dll hell problems by only coupling to my service contract instead of a set of com+ interfaces.

I agree that there are cases where you want to use a service inside an application, especially if you plan to reuse the service to build other applications. The point I was making was that people carrying the WS hammer may have a tendency to see everything as a WS nail. They run the risk of repeating a mistake others have made before when they tried to treat every C++ class as a COM component or every COM component as a COM+ component. There is overhead in being a service and you don't want to incur it if you don't have to.