Together, BPM and SOA provide a perfect combination for enterprise computing. BPM provides the higher-level abstraction for defining businesses processes, as well as other important capabilities of monitoring and managing those processes. Services provide the functions that support those processes. SOA provides the capabilities for services to be combined together and to support and create an agile, flexible enterprise. BPM without SOA is useful for building applications, but difficult to extend to the enterprise. SOA without BPM is useful for creating reusable and consistent services, but lacks the ability to turn those services into an agile, competitive enterprise.
In other words, SOA provides the design philosophy and enterprise context for building services, and BPM orchestrates those services. Two great tastes, together at last.
He also discusses the practice of creating relevant services based on the required functionality of the enterprise, rather than just putting lipstick on the pig by developing a pass-through wrapper around each legacy application. There’s a good diagram in the article (it’s a PDF, so I can’t link to it directly) showing the layers and linkages involved.