Alex Garrett have written a good article about developing eBay applications with PHP5 and Web services.

create applications in PHP5 that interact with eBay through Web services. Almost half of eBay’s transactions occur through its Web services platform. In this tutorial, you’ll acquire a solid understanding of the mechanics of the eBay XML API and learn how to use the Services_Ebay PHP extension

In this part 3 of the tutorial you can learn how to

  • Write your own eBay XML API test tool.
  • Register users and retrieve their authentication tokens.
  • List items with Services_Ebay, either as an API call or as a behavior on the Item model.
  • Execute eBay searches through the API.
  • Capture the response XML and bypass the models in Services_Ebay.
  • Retrieve and handle API errors.
  • Debug calls made through Services_Ebay.
  • View the internal documentation in each Services_Ebay call class.

IBM is recently interested into PHP after their collaboration with Zend to develop ZendCore for IBM. An excellent alliance to bring PHP to entreprise level and we see already articles about PHP on the IBM developerWorks.