Adam Trachtenberg has posted, according to this new item on his blog, the slides from his presentation at this year's OSCON. The title of the talk? "Dirty Secrets of PHP 5's ext/soap Extension."
The slides [pdf] summarizes his talk, described as:
PHP 5's ext/SOAP extension is an excellent web services client. However, while the easy things are easy, lack of documentation means the hard things can appear downright impossible. Starting with SOAPClient basics and building upwards, learn the hidden secrets necessary to conquer even the strangest WSDL.
In the presentation, he not only describes the functionality the PHP 5 extension offers, but provides a few simple code examples to help with the explaination.