The PHP project has released the latest in the PHP 5.3.x and 5.4.x series today - PHP 5.4.8 and 5.3.18:

The PHP development team announces the immediate availability of PHP 5.4.8 and PHP 5.3.18. These releases fix over 20 bugs. All users of PHP are encouraged to upgrade to PHP 5.4.8, or at least 5.3.18. Key enhancements in these releases include: fixed bug #63111 (is_callable() lies for abstract static method) and fixed bug #61442 (exception threw in __autoload can not be catched.

You can get this latest version from the downloads page (source) or from Windows.php.net for the binaries. The full list of changes are in the Changelog.