As a counterpart to PHP 5.2.1 that was released a few days ago there is now an equivalent security release of PHP 4.4. This addresses most of the same issues as PHP 5.2.1, but also some PHP 4.4 specific issues. I recommend to upgrade as soon as possible to PHP 4.4.5 if you're still using either PHP 4.3.x or PHP 4.4.y [with 0 <= y < 5]. You can download PHP 4.4.5 from the [link http://www.php.net/downloads.php#v4]PHP website[/link].
The PHP 4.4 branch is "maintenance" only, meaning that releases are primarily only made for security and other important fixes. Of course, less important fixes can also make it into the release in case this is deemed useful.