Today, we are pleased to announce that AdWords API v2009, which we released to a limited whitelist in June, is now available to all API users! Compared to previous versions of the AdWords API, v2009 offers you new features and greater speed at a lower cost.
To get started writing code for v2009, check out the developer documentation on the v2009 homepage. Additionally, we have 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 it is your current Google Account username and password. Beforehand, read up on sandbox best practices.
John Fitzpatrick, AdWords API Team