Google announced that starting today, you will no longer have to provide them with an AdWords API application token to access the AdWords API (v13 and v2009). No change is required on the part of the developer.
Application tokens will now simply be ignored if they continue to be included in API requests. The company does, however, remind developers that the developer token is still required. This is described here:
Uniquely identifies the developer and is used to track your API unit usage. To safeguard your privacy and protect yourself from fraudulent charges by other users, you should not share your Developer Token with other users. You can find your Developer Token listed on your AdWords API Center, accessible from your My Client Center’s “My Account” tab.
“We hope that this makes your life a bit easier in working with the AdWords API,” says Albert Cheng with the AdWords API Team.
Cheng also reminds developers that Google will answer questions, collect feedback, and assist with migration to the v2009 API via the AdWords API forum.