The first release on the path to PHP7 has officially been released according to this new post on the main PHP.net website - PHP 7.0.0 Alpha 1.
The PHP development team announces the immediate availability of PHP 7.0.0 Alpha 1. This release marks the beginning of the PHP 7 major series. All users of PHP are encouraged to test this version carefully, and report any bugs and incompatibilities in the bug tracking system. PHP 7.0.0 Alpha 1 comes with new version of the Zend Engine with features. [...] For more information on the new features and other changes, you can read the NEWS file or the or the UPGRADING file for a complete list of upgrading notes. These files can also be found in the release archive.