eBay has certified iPhoneAppLab's "iPhoneMyeBay" iPhone-optimized Web app for use with its services. In the words of the developer:
"eBay has put the application through rigorous QA testing and said that it meets it qualifications for working with eBay APIs and providing users of the applications all the benefits available."
Most importantly, however, this means that users can now actually bid on eBay items through the Web app. The bidding words on all auction types, and you can use a regular bid or "Buy It Now."