Tutorial for Services_Ebay :: a programmer's best friend

Adam Trachtenberg, manager of Technical Evangelism at eBay, has written an introductory tutorial on Services_Ebay, one of my newest PEAR packages.
Although this ONLamp.com tutorial is rather short, it deals with some interesting aspects of Services_Ebay, as he shows what can be accomplished by object-overloading and he even makes use of the ability to switch model classes in a way I've never thought of them. Adam implements his own models to use them as a presentation layer as he only changes the output of the __toString() method.
If you are interested in the Services_Ebay package, this is the tutorial that will get you started.