“Please let me know if I should stop developing apps for Google Products”
If you build something on someone else's API, you can get fucked in a million ways. They might shut down the API (Google Reader), take away the functionality you relied on (Google Calendar), limit it (Twitter) or deprecate the version you're using, forcing you to do development work to keep working at the worst possible time for you (IOS). They might also decide that your product is very good and build a version of it themselves, using functions not available to you via the public API so that you cannot compete with it (Apple).<p>So before building something that relies on things entirely outside of your control, consider a few things and the effort it would take for each:<p>- Can you run it on something else (S3 is a good example - there are several API-compatible competitors)
- Can you replace the service you're relying on with one of your own (e.g. building your own Google Reader sync API)<p>Then decide if it isn't worth building the whole thing yourself. Heck, you might even want to put an API on it yourself. Feel the power? :)<p>Oh, and never, ever rely on someone else doing authentication for you. It's just too easy to get your entire userbase taken away from you.