The Google API I was using had a 6 month lead time, no recommendations for graceful transition, no offer of data dumps, and the final shutdown date was never communicated.
The API I was using, was shutdown without any communication. (Adsense for ajax - announced at Google I/O 2010). They simply closed my account without paying the money I was owed (substancial sum). I later found out from a Gooler "yeah they decided to shutdown the product".
Beware of relying on anyone, even a big company who says they won't be evil.
Hahahahaha no. They don't. If only they did anything remotely as nice as that.