On PHPMaster.com today they've posted their series on "speaking REST" (part one is here), developing a PHP-based RESTful framework.

In the first article of his series, David explained how REST is more than an architectural pattern. It's a set of guiding principles that, if followed, can help you write scalable and robust applications. In the following articles, David will resume the discussion by looking at REST from the client-side of the equation. In this article though I'd like to focus on the server-side. You'll learn how to shift your thinking from the action-focused mindset that's prevalent in web development today to a more RESTful, resource oriented, approach, and see one way to structure your code and route URI requests in PHP.

He talks about the change in mindset it takes to create an effective, resource-focused RESTful service and shows some of the initial steps towards getting it all down in code (based on a simplified "front controller" that routes the request appropriately). The resources are defined as classes (like the "Restaurant" in their example) which then handles the type of request based on the request type (GET, POST, etc).