I have been asked by several people to write in more detail about what I meant by the layered approach, so I thought it should be better illustrated in an architecture diagram (converting it to picture did not result in high quality, somehow). The rationale behind it that event processing became pervasive in use, with both event processing products, and "build your own solution". In the same way that application servers based on standards like J2EE contributed to building of certain type of web-based enterprise applications, an application server for event-based applications is required to provide services from various types: from context service, adapters to sensor and mobile platforms, dashboard, management services, meta-data service and more. The second layer is the agent layer which provide both directory of agents and tools to build your own agent. The application is the third layer. This architecture can provide independence, and ability to get best of breed in both services and functionality components from different sources, and combinations of "build" and "buy".
Standards are of course the key to make it happen.