For almost 5 years now, we've been advising clients on their SOA scorecard. In the early days of SOA adoption, customers often measure their success by 'releasing services'. This is a great metric for beginners. As the program progresses the shift moves to their utilization. Services are only valuable if they are actually used. From this perspective, we recommend looking at the consumer-to-service ratio as the primary test. The secondary test looks at message counts; that is, are the services actually being called.
Unfortunately, neither of these tests actually look at the value that software brings to the business. We've been encouraging our customers to spend more time looking at the business proposition that the service reflects. Business strategy is based on those activities and assets which are considered 'Sustainable Competitive Advantages' or SCA. These are the things that allows a company to be successful in their business year after year. Strategist have various means of identifying and describing the SCA's. Moore's 'core vs. context', and 'value chains' are often applied to help an organization understand where they need to be competitive.
Many organizations have moved beyond SOA pilots and now have scores of services running in production. However, many of these same organizations do not have the truly important services available. The fixation to increase the number of services often overrides the commonsense notion of providing business-valued services.
I've been encouraging customers to look at the three C's of business: Customers, Commerce and Channel. All three of these domains are typically excellent candidate for service enablement with high business value. Obviously, there are other domains that might be more important for your business which should be prioritized higher. The point is that you need to create a priority list of services based on the business that you're in. Service enabling non-valued added aspects of the business might look good on an old fashion SOA scorecard, but it no longer passes the smell test!