If you've been looking for the "quick and dirty" definition of all of the changes that come with the latest version of PHP 5.4, you should check out this new post from Sameer Borate. It has a quick rundown, code included, of these new features and changes.

Although purists have always sneered upon PHP for being a “patched” language; the evolution of PHP over the years, with new features added in every version, has only increased its popularity. The latest 5.4 release has followed the trend with some major feature additions. The following post describes some important changes in PHP 5.4.

His list includes: the updated array syntax, the bulit-in web server, array dereferencing, traits, upload progress tracking and various core changes to things like the short syntax for calling static methods in classes and the complete remval of magic quotes.