As a PHP developer, you need the following information.
The PHP development team announces the immediate availability of PHP 5.4.6 and PHP 5.3.16. These releases fix over 20 bugs. All users of PHP are encouraged to upgrade to PHP 5.4.6, or at least 5.3.16. For source downloads of PHP 5.4.6 and PHP 5.3.16 please visit our downloads page, Windows binaries can be found on windows.php.net/download/. The list of changes are recorded in the ChangeLog.
Bugs fixed in these two releases relate to things like bugs that were causing crashes in auto_prepend_file on the CLI web server, a segfault when DateInterval was extended, a return type on PDO and a fix for the count() call on an IteratorIterator. See the ChangeLog for the full list.