One thing that I find incredibly fast and easy to do on iOS6 vs. iOS5 is implementing post-to-Facebook (and Weibo) using the new Social Framework. In iOS5, you would have to

- Register your app on Facebook

- Integrate the FB SDK (or maybe a third-party wrapper)

- Implement various authentication/delegates/callbacks

- Test that you did all of these things correctly

This might not sound like a big deal but it does save some time.