Rob Richards is the author of Pro PHP XML and Web Services. He literally wrote the book on using PHP and XML together. At php|works, he is leading a tutorial on using XML in web services using the DOM extension.

If you ever get a chance to hear Rob do a presentation, let me warn you, it is not for the faint of heart. As I learned last night when I sat down with Rob to record an interview, Rob likes to speak on leading edge and advanced topics. This tutorial is an excellent example of that philosophy.

Cal talks more about the content of the talk - its simplicity despite the complex topic, how much info is jammed in, and the fact that it's not just one giant pitch for Rob's book.