On PHP.net they've posted the official announcement about the release of PHP 5.3.8, an release following 5.3.7 to fix some issues with the crypt functionality.
The PHP development team would like to announce the immediate availability of PHP 5.3.8. This release fixes two issues introduced in the PHP 5.3.7 release: Fixed bug #55439 (crypt() returns only the salt for MD5), reverted a change in timeout handling restoring PHP 5.3.6 behavior, which caused mysqlnd SSL connections to hang (Bug #55283). All PHP users should note that the PHP 5.2 series is NOT supported anymore. All users are strongly encouraged to upgrade to PHP 5.3.8.
As always you can download this latest release from the downloads page (Windows binaries here). This upgrade is highly recommended if you were running 5.3.7.