The PHP development team announced yesterday that PHP 5.3.3 and 5.2.14 are now available for download.
This newest version of 5.3 includes more than 100 bug fixes - some of them are security related. All users are encouraged to upgrade as soon as possible.
But before you do, make sure you aren't using namespaced classes with a same name method as a constructor - that doesn't work anymore. Classes that aren't namespaced are not affected.
And to anyone who's still running PHP 5.2, this release marks the end of active support for 5.2. Security fixes will be published on a case by case basis.