It is becoming a worrying trend that developers (even those of the more popular services and frameworks) do not know or respect semantics of the HTTP protocol:

CakePHP tutorial
del.icio.us API
Ruby on Rails tutorial from O’Reilly

All of these examples are proposing URLs such as /users/delete/1 or /posts/add for editing or deleting resources via the HTTP GET method. While they probably pretend to be RESTful, they are in fact breaking HTTP and REST semantics. HTPP 1.1: Method Definitions states that GET and HEAD methods SHOULD NOT have the significance of taking an action other than retrieval. These methods ought to be considered “safe”. and that GET is idempotent. In other words, sending GET request should not change server state.
UPDATE: Not Ruby on Rails itself, only a tutorial on it.

Tags: CakePHP, Frameworks, PHP, Resources, Ruby, Ruby on Rails, Tutorial, XML