As Andrew confirmed above, that script defaults to PHP 5.2
I have the logic mapped out to handle all versions (even future) in one script but it needs more work on the design side before I throw it out there. Sorry about that.
DreamHost (actually I think Andrew might have had a lot to do with it) made it super easy for us to load extensions with the new intelligent system that was rolled out with 5.3 – i.e. default parsing of per-user phprc’s. If you require 5.3 and are following the wiki, read just the few lines mentioning “phprc” and ignore everything else.