There's a new project over on SourceForge that has been getting a lot of linkage through del.icio.us - the APIlity PHP Library.

The APIlity PHP Library provides an object-oriented way to easily access and manage the Google AdWords API from within PHP. This comes along with an abstraction from the SOAP and WSDL details.

With the AdWords API you can not only manage and organize your accounts more efficiently, easily and smoothly, but also more creatively. Using the API, you can create your own report-pulling software, synchronize your bids with your warehousing or have your own mass uploading tool control your accounts.

With the huge success of the Google AdWords system, I can see why something like this would catch on. And they seem to have already put a lot of work into it with a large list of functions/functionality already supported...