Windows Workflow Foundation (WF) offers rules capabilities to the WinFx developer platform. You can utilize WF rules to define and execute rule sets on any target object. I wrote a Rules Driven UI sample to demonstrate these capabilities and posted it here on WF community web site. The sample executes WF rule sets to populate fields, do cross validation, and various calculations on a target Windows form. Check it out.
If you want to learn more about Rules capabilities, check Jurgen Willis’, MSDN Article “Introduction to the Windows Workflow Foundation Rules Engine” here.