Amazon Web Services introduced the world to a new, completely rewritten SDK for PHP 2.0.0 . Written on the Guzzle HTTP framework , the new SDK presents the user with the ability to support persistent connections and better network performance. It also became possible to quickly integrate with the Symfony2 event manager for developing hooks.
You can get acquainted with the SDK on this page . Of course, a more interesting description of the features can be found on the project's GitHub repository.