The newest features from the adCenter Spring 2009 Upgrade and several key API improvements are now available to you. API Version 6 will replace API Version 5.1 in the coming months. We recommend that you familiarize yourself with the new features and plan to upgrade your WSDLs to Version 6 to avoid service interruptions later this year. We will continue to support Version 5.1 for up to six months, and we will provide more information about its sunset in the coming weeks,” stated Chris Norred.