The PHP.net site has posted about the release of PHP 5.5 beta 4, the last beta that will be made for this series.
The PHP development team announces the release of the 4th beta of PHP 5.5.0. This release fixes some bugs against beta 3 and cleans up some features. This is a development preview - do not use it in production.
Several bugs were fixed and changes made - you can read the complete list in the NEWS file. To get this latest beta and try it out with your applications (and run the tests) you can download it here (here for Windows).