Currently the XACML project provides the core functionality and the PDP. The PEPs are essentially in the integrating projects such as JBoss Application Server etc (web, ejb containers). The XACML project is a lightweight project that does a few things very well.
If we want to add some of the enterprisey things, I would suggest we create a complementary project under the picketbox umbrella and add those goodies there. That way, people who are looking for a core xacml engine can use the xacml project and people with enterprisey standalone xacml capabilities - can get the core xacml project + enterprise project together.