http://www.php.net/downloads.php#v5.1



  • PDO (PHP Data Objects) - A new native database abstraction layer providing performance, ease-of-use, and flexibility.
  • Significantly improved language performance mainly due to the new Zend Engine II execution architecture.
  • The PCRE extension has been updated to PCRE 5.0.
  • Many more improvements including lots of new functionality & many bug fixes, especially in regards to SOAP, streams and SPL.
  • See the bundled NEWS file for a more complete list of changes.