Here at Vordel we'd certainly welcome this initiative. As an XML Gateway vendor, we have built interoperability with many authorization products such as CA/Netegrity SiteMinder, IBM Tivoli Access Manager, Entrust GetAccess, etc etc etc. In many cases this interoperability involved the use of APIs rather than the use of the XACML PEP/PDP model. If XACML was used in a standard manner across the board, then that would have helped us a lot. As it stands, we built all the connections anyway, but we still expose a XACML PEP/PDP interface ourselves so that our customers can take advantage of this. I've written about Vordel's XACML PEP/PDP support and experiences here: http://radio.weblogs.com/0111797/2007/01/22.html#a73 cheers -Mark