Rules Engines for .NET

This morning I was asked about my recommendations for rules engines. On the Java side I’ve always recommended Drools or Jess (though there are many more Java-based open source engines listed on this site). The .NET rules engines that I’m aware of include NxBRE, QuickRules, and InRule. This thread on ServerSide.com presents a simple rules engine with source code along with a discussion that includes references to other available engines.