IBM recently announced "Websphere Decision Server". This announcement states that this offering combines business event processing with business rules management system to accelerate decision making.
There are several ways in which event processing and business rules interact, some of them are: an event, derived by pattern detection, triggers a rule, which makes it event-driven decision; the other direction is also valid: an execution of rules brings into decision and this decision can be reported as an event and may influence other decisions. Triggering decisions is one of the major uses of event processing (of course it is not the only one, e.g. event processing can be used for diagnosis or information dissemination), and it is a component in the automated decision making process, but these components mainly exist within islands (EP, business rules, optimization software and other means of decision support systems). One of the areas we are working on (we had a short report on it within the "fast abstract" session of DEBS 2010, as we were not in a position yet to deliver a full paper) is a unified conceptual model of event processing and business rules, where both are generalized as decision agents. this is still in the research phases, and not part of the product, nevertheless this announced offering provides step forward in achieving such an integration. More synergies in the decision space are expected.