I've just run all the PsychoPath XPath 2 processor (an Eclipse Web Tools, Source Editing sub-project) W3C test-suite tests, and here are the results for them:
So it seems, PsychoPath XPath engine passes, 100% of the W3C XPath 2.0 test suite, and some of it's own tests.
This should be a moment of cheer, and wow!
It also looks, like that the upcoming Xerces-J release, 2.10.0 (ref, http://wiki.apache.org/xerces/November2009) would be getting almost a compliant XPath 2.0, engine for XSD 1.1 assertions and CTA.
Ref: An earlier post about PsychoPath status: http://mukulgandhi.blogspot.com/2009/09/psychopath-xpath-20-processor-update.html.