On the Cake Baker's Blog, there's a handy example for anyone out there using the CakePHP framework wanting to reach out and touch someone with SOAP.
The code in this post is derived from the example presented in the article "Using PHP5's SOAP Support". You find explanations there, I will only describe some CakePHP specific things.
The simple example defines the model (where the real action happens), a simple controller (basically setting the output), and a simple view (echoing it out is the easy thing to do). His example makes a request out to the Amazon web service and searches the "books" category for items matching the term "php".