Changes to an API Terms of Service (TOS) are an inevitable part of API operations, and as API owners work to evolve their APIs, changes can often be at odds with the community. As some API seem to struggle with the best way to update, Google's approach appears to be more balanced. Google just updated its TOS for Google Earth and its popular Google Maps API.
One of Google's oldest APIs--and the one most closely aligned with how the company makes money--will disable old versions of the Google AdWords API at the end of February. If you're using an app to enable keyword buys, or are using the API directly yourself, you'll want to make sure you're using v201109.