In this quick post to his blog Arnold Daniels points out their patched version of the Suhosin hardening patch for PHP 5.3.

The hardened-php project has yet to release a suhosin patch for PHP 5.3.0. We’re already using PHP 5.3, therefore I’ve modified the 0.9.7 patch for 5.2.10 to work with 5.3.0.

The Suhosin patch, created by the Hardened-PHP project is a protection system aiming to help protect your PHP installation from some of the common (and not so common) flaws in the PHP language itself. It's applied as a patch to the source before compiling and gives you a list of features for the base engine, runtime, session and filtering protection.