Not sure if I'm being too reckless, but this seems to be working fine for me, and it certainly looks more efficient in my eyes:
<?php
$node = node_load(arg(1));
$type = $node->type;
return in_array($type,array('my_content_type'));
?>My PHP coding background is certainly more developed than my Drupal background, so please let me know if I'm doing something I shouldn't be doing!
Més exemples i explicacions a: http://drupal.org/node/134425
