Now I've started working on a XML-PULL parser for PHP, the concept of a pull parser is pretty interesting and there're some Java implementations, descriptions and APIs at www.xmlpull.org.
Now with the introduction of a non-Java implementation the need for a language neutral test-suit has arisen, one idea is to write the tests using an XML vocabulary and then convert the test to PHP/Java/Others using XSLT, once the XMLTEST->Code XSLT is built any test can be run on any platform and that's cool.
The xmlpull.org people will work on a first version of the test vocabulary and I'll try to write the XSLT stylesheet for PHP when possible.