Paul Vincent has posted in the TIBCO Blog a post entitled: "event server as the 21st app. server".
Paul cites TIBCO CEO Vivek Ranadivé in TIBCO's quarterly earning report, and concludes that an event server will is a requirements in many applications that process events in various ways.
Getting to the notion of application server (see illustration below taken from an article on Websphere Application Server)
Application servers are intended to support services to applications such as: transaction, storage, database approach, security, high availability, administration and more.
In the event-driven world there are flowing events, and with the Internet of Things, most data in the universe will be in form of events. In the event processing manifesto (that Paul has been one of the contributing members to its creation) we talked about "event fabric" which will enable Internet scale sharing of events and will support many applications. Some of the fabric properties mentioned were providing services of privacy, security, interoperability among fabric instances, provenance, energy efficiency, autonomic computing support (self-tuning etc...), availability, scalability, anonymity, non-repudiation, QoS with multiple criteria. These are some of the services, and there are of course functional services like context service, adapter and transformation service, filtering service, aggregation service, pattern matching service and more that should be built into the server and can be used by various applications from various application areas and types (BPM, CRM, Social computing, track and trace and many more).
Paul rightly notes that standards have key role in establishing such event server, Paul indeed wrote the standards chapter in the manifesto.
I think that the equivalent of app server based on events is inevitable since events will be at the heart of all applications that take sensor data an input. Work on standards in this area is an old dream, and hope that we'll be able to advance towards it.