cameraman - 7:11 am on May 1, 2007 (gmt 0)
responseXML is not populated. ;)
Inneresting, I didn't realize that.
I did some experimenting, and if a text/xml content-type is returned, it does get populated (I don't know how fully - I just extracted the title and paragraphs). You could do a gateway script that serves the requested page with an xml header and manipulate it from there.