I got an update on the Oracle Business Rules product recently. Oracle is an interesting company - they have the components of decision management but do not yet have them under a single umbrella. For instance, they have in-database data mining (blogged about here), the Real Time Decisions (RTD) engine, event processing rules and so on. Anyway, this update was on business rules.
R. Bruckner, B. List, and J. Schiefer. DaWaK 2000: Proceedings of the 4th International Conference on Data Warehousing and Knowledge Discovery, page 317--326. London, UK, Springer-Verlag, (2002)