Hasin Hayber has posted about a new library he and his group have created to interface directly with the RackSpace Cloud Server API - phprackcloud.

So we have spend our time for last two days and developed a PHP client library to use RackSpace cloud server API from inside a PHP application. [...] There is plenty of documentation and example included. The code is mostly self explanatory. Please don't forget to check the Wiki page to get some idea on how to use this library and how far you can go. We have covered all available methods by RackSpace cloud server in our client library.

Davey Shafik also added a comment to the post about an interface of his own that uses parts of the Zend Framework to make and handle the request.