I have written in the past about event processing in simulation mode, recently an article on the IBM developerWork describes an Infosphere Streams implementation of traffic simulation.
The picture above is taken from the article, a vehicle generator generates simulated events of vehicles. Each round represents 1 second in real-time and cars are accelerating, stopping and behaving according to traffic rules. This is an example where the stream processing is done not on real-life events, but on simulated events. The reported benefit of using streams have been the large scale of this simulation (multiple vehicles, rounds of 1 second, multiple streets). Besides the scalability aspects, much of the simulated behavior may be expressed using operators on events. Simulation has been one of the first areas that use some type of event processing, and using event processing for simulation closes a circle.