New features
Deprecated features in PHP 5.4.x
Migrating from PHP 5.3.x to PHP 5.4.x
PHP Manual

## Changes in SAPI modules

- A new SAPI module named cli-server is now available.
- Added CLI option --rz which shows information of the named Zend extension.
- Added shortcut #inisetting=value to change php.ini settings at run-time in interactive readline CLI
- Added apache compatible functions: apache_child_terminate(), getallheaders(), apache_request_headers() and apache_response_headers() for FastCGI SAPI.
- PHP-FPM: Added the process.max setting, to control the number of processes that FPM can fork.

New features
Deprecated features in PHP 5.4.x
Migrating from PHP 5.3.x to PHP 5.4.x
PHP Manual