The PHP development team would like to announce the immediate availability of PHP 5.3.15. This release fixes over 30 bugs and includes a fix for a security related overflow issue in the stream implementation. All users of PHP are encouraged to upgrade to PHP 5.3.15
PHP 5.3.x includes a large number of new features.
Some of the key new features include: namespaces, late static binding, closures, optional garbage collection for cyclic references, new extensions (like ext/phar, ext/intl and ext/fileinfo), over 140 bug fixes and much more.
For users upgrading from PHP 5.2 there is a migration guide available here, detailing the changes between those releases and PHP 5.3.x.
The full list of changes is available in the ChangeLog.