On the PHP.net site today there's an announcement about the release of the PHP 5.4 alpha1, the first version of the upcoming 5.4 release.

The PHP development team is proud to announce the first PHP 5.4 alpha release. PHP 5.4 includes new language features and removes several legacy (deprecated) behaviors. Read the NEWS file for a complete list of changes. [...] This alpha release exists to encourage users to identify bugs, and to ensure that all new features and backward compatibility breaks are evaluated and documented before PHP 5.4.0 is released. Please report findings to the QA mailing list and/or the PHP bug tracker. Windows binaries can be downloaded from the Windows QA site.

They remind the development community that this is an alpha release and is not meant to be used in production. Changes in this release include traits, array dereferencing, DTrace support, the removal of several ini options and a few session-related functions.