From PHP.net :
The PHP development team is proud to announce the fourth release candidate of PHP 5.3.0 (PHP 5.3.0RC4). This RC focuses on bug fixes and stability improvements, and we hope only minimal changes are required for the next candidate or final stable releases. PHP 5.3.0 is a newly developed version of PHP featuring long-awaited features like namespaces, late static binding, closures and much more.
Please download and test these release candidates, and report any issues found. A stable release is expected next week . In case of critical issues we will continue producing weekly RCs. Downloads and further information is available at qa.php.net. See also the work in progress 5.3 upgrade guide.
The preview packages for Debian GNU/Linux 5.0 “Lenny” on amd64 and i386 has been updated. Just apt-get upgrade.