My simple RE is the former... multiple conditions and actions are set for a rule; only if all conditions are met are all actions performed. However it could instead work like a flowchart, where each condition can have true/false execution paths. While that's more powerful, it doesn't really seem like a rule any more... more like a scripting/programming language.
Thoughts welcome.
You should take a look into Microsoft Windows Workflow Foundation Rules Engine:
The rules capability allows for the declarative modeling of units of application logic within the scope of an overall business process. Sample scenarios for rules engine technology are order validation, pricing calculation, promotion enforcement, exception process management, and claims adjudication and management.