I've created a mapping of the JBoss jBPM 3.1 hibernate mapping using Linguine Maps.
The PDF is 40" x 70" for plotting on an HP DesignJet, or similar device.
You can also view a PNG of the model. See the Wiki page here:
http://wiki.jboss.org/wiki/Wiki.jsp?page=Jbpm31HibernateModel
wow.... I never inspected the hibernate mappings closely, but that it was this complex.....