How PHP chokes on <?xml tags when short tags is enabled is compleltely
silly. There's a patch here to fix it,
http://news.php.net/php.internals/18493, some proof of why it's a problem,
http://news.php.net/php.internals/18496, and the "bogus" (yeah, right) bug
report, http://bugs.php.net/bug.php?id=25987.
As the author of the patch you mentioned, I should reitterate that I don't think that it's a *good* fix. Treating <?xml as special is a hack, not a broadband solution.