OS X 10.9 will ship with PHP 5.3
Looks like the next iteration of OS/X will still again not ship with a recent PHP version. The reported version appears to be:
PHP 5.3.23 with Suhosin-Patch (cli) (built: May 22 2013 00:00:34) Copyright (c) 1997-2013 The PHP Group Zend Engine v2.3.0, Copyright (c) 1998-2013 Zend Technologies
While it’s a version from March this year, PHP 5.4 was already released before the release of the last OS X (10.8/Mountain Lion).
Looks like I was in the wrong. The latest beta releases now do ship with PHP 5.4. Sorry for jumping to conclusions!