Google announced that AdWords API v2009 is now available to all API users! Because it offers nearly all of the campaign management functionality you're used to from the AdWords API, along with a new rate sheet representing lower costs, now is a great time to start developing. Check out the developer documentation on the v2009 homepage. Additionally, a v2009 sandbox available to all users for experimentation and testing. The sandbox doesn't charge for API units, and all you need to access its your current Google Account username and password.