AS per this announcement on the Zend Developer Zone, Zend has released the latest version of their Zend Core product updating it for PHP 5.2.3.
The Zend Core team has just released PHP 5.2.3 as an automatic update, so you should be able to upgrade your Zend Core environment with the latest PHP - in one easy step. (Zend Core 2.0.3 Windows packages are also available).
Updates in the latest release include improved Windows performance and reliability, a bundled Zend Framework and universal database support. You can download the latest version from the Zend Core page on the Zend website.