The latest version of PHP can be downloaded from Softpedia
PHP, an HTML-embedded scripting language with syntax borrowed from C, Java, and Perl, with a couple of unique PHP-specific features thrown in, has been updated to version 5.5.7 RC1.PHP 5.x includes a new OOP model based on the Zend Engine 2.0, a new extension for improved MySQL support, built-in native support for SQLite, and much more.
PHP 5.5.7 RC1 features a large number of improvements and fixes. For example, some MIME types have been added to the CLI web server, unregister_tick_function no longer tries to cast a Closure to a string, an invalid constant substitution has been fixed, inconsistent results with require return value have been fixed, and more.
You can check out the official changelog in the readme file incorporated in the source package for more details about this release. Download PHP 5.5.7 RC1 right now from Softpedia.
Remember that this is a development version and it should NOT be installed on production machines. It is intended for testing purposes only.