The PHP.net site has posted the release announcement for the latest PHP version in the PHP 5.3.x series - 5.3.2:

The PHP development team is proud to announce the immediate release of PHP 5.3.2. This is a maintenance release in the 5.3 series, which includes a large number of bug fixes. [...] For users upgrading from PHP 5.2 there is a migration guide available here, detailing the changes between those releases and PHP 5.3.

Security/bug fixes included in this release take care of things like:

• Safe_mode validation inside tempnam
• A possible open_basedir/safe_mode bypass in sessions
• Added support for SHA-256 and SHA-512 to php's crypt.
• Fixed a bug in the garbage collector that could cause a crash
• Crashing when using ldap_next_reference

For more information on the release and what was fixed see the Changelog. You can download this release immediately - source code or Windows package.