We have done lot of work with this JSR specially we used it a lot during the design of JSR 233.

Is there anything specific that you need to know?

You can see Drools (http://drools.org)
See also http://drools.org/JSR-94+TCK+Tutorial

Drools is an open  source rule  Engine which you can really trust on. We used this engine  in one projects with really heavy business rules. It meet all the requirements you need.

Recently, it's been as a JBoss product, called JBoss Rules. You can use version 2 or 3, depending on your need. Because these two versions are completely different.

u can get help from http://www.openrules.com
its good for begining of OpenRules projects

jboss have also a rules engine:

http://labs.jboss.com/portal/index.html?
ctrl:id=page.default.info&project=jbossrules

Hi,
JSR-94 is only a thin API around a rules engine and that too is fast losing its importance. If you need a simple, rules engine having plain english rules and allows running if-then type rules, please check out 'Acuity Business rules composer' from concentricsys.com.

cheers,
Om
founder and ceo,
http://www.concentricsys.com
Business rules for everyone