The official start of the PHP 5.5.0 release process has started today with a new post from David Soria Parra and Julien Pauli about the release of the "alpha 1" version of the release now being available for testing. (Note: this is an alpha release and is by no means suitable for real-life usage).

As announced a few weeks ago, we tagged PHP 5.5.0alpha1 on Tuesday. This release marks the start of 5.5.0 release process. [...] This release includes a dozen new features, such as Generators, List support in foreach. the simplified password API, and many more. Thanks to everyone working 5.5.

The plan is to put this out there for testing and then tag "alpha 2" on the 27th and make the actual release on Thursday, the 29th. If you'd like to help with the testing, download the alpha and run your tests (including the "make test" on install). Windows builds are also available at windows.php.net/qa.