The PHP.net site has announced the release of the latest beta for the PHP 5.5 series - PHP 5.5 beta2:

The PHP development team announces the release of the second beta of PHP 5.5.0. This release fixes some bugs from beta one that could prevent the release from compiling. [...] Our next beta is expected for April 11th.

This is a development preview, so do not use it in production. Several bugs were fixed in this beta release - you can view the NEWS file for a complete list. If you'd like to help test it out in your environment and with your applications, go download it (Winodws) and give it a shot. You can provide issues you might find back to the bug tracker.