There's actually a PHP-XML list on wrox.  I remember posting a while back
something about xslt and sablotron for PHP, and the moderator subscribed me
to that list and posted my message there.

I don't think there's been any activity on that list for quite some time.

I didn't realize just how many PHP lists there are on wrox now... but I
doubt that any of the other ones are as active as pro and beginning (i'm
only subscribed to this one.)