For the most part this won't affect users - except for the Google Translate API. That one is going to shut down in 6 months, and any app that relies on it will stop working. There are 11 APIs that have been deprecated but will continue to function for 3 years. If you have a news fetching app, it might rely on either the Blog Search or News Search APIs.
- Blog Search API
- Books GData API - replaced by a new Books API
- Image Search API
- News Search API
- Patent Search API
- Safe Browsing API version 1 - replaced by a new Lookup API
- Translate API - deprecated now, shut down December 1st
- Transliterate API
- Video Search API
- Virtual Keyboard API
There are 7 more APIs that have been deprecated but don't have a shut down date:
The Feedburner API is another one that could hurt, but I'm not sure anyone's using it. Feedburner runs so slow most of the time that I would suspect that mostr developers have junked it in favor of something else.