PHP 5.2.3 will probably be released in the next week or two unless major problems are discovered. You can test Release Candidate 1 right now if you have a Linux platform to load it on. Head over to http://downloads.php.net/ilia/ to get php-5.2.3RC1.tar.gz. There isn't an RC version available for Windows right now so you'll need to load it up on Linux.
If you need a decent Linux platform to test with then get yourself a copy of href="http://www.debian.org">Debian, or Ubuntu, or Kubuntu if you like the KDE desktop better than Gnome. Those are good choices for admins that aren't very familiar with Linux.