The PHP development team is proud to announce the second release candidate of PHP 5.3.0 (PHP 5.3.0RC2). This RC focuses on bug fixes and stability improvements, and we hope only minimal changes are required for the next candidate (RC3). Expect an RC3 in 2-3 weeks, although there will not be major changes so now is a good time to start the final testing of PHP 5.3.0 before it gets released, in order to find possible incompatibilities with your project. Please download and test this release candidate, and report any issues found. Downloads and further information is available at qa.php.net. See also the work in progress 5.3 upgrade guide.

Source: http://www.php.net/index.php#id2009-05-07-1