PHP 5.3 was released 6/30/09. It brings [url=http://us.php.net/manual/en/migration53.new-features.php]some big changes[/url] to PHP — among them: namespaces, closures, a few shortcuts, nowdoc, and changes to heredoc and PHP.ini.

Be sure to read the [url=http://us2.php.net/migration53]Migration Guide[/url] before upgrading to the latest and greatest.