good news to all Drools-users - they just released version 3.0.6 of JBoss-Rules.
In my current project we use pretty simple rules without dynamic assertions and all that non-declarative salience mumbo-jumbo - and Drools worked fine since Version 2.x. We're really happy with the product. We're by no means happy with their handling of bugs, though - but as we encountered no critical ones so far, that's ok too.
Rule-understandability has improved a lot since Drools 2.0, so has the documentation (all right - its a little away from perfect). Overall result after more than 12 month of experience: very positive.