If things change drastically, we'll likely write up a blog post or even a newsletter. Many rollouts of changes (even if they have a specific date announced) actually happen over a matter of weeks and it's not always a binary "This broke, that works". Due to the rollout, what still works for us may have broken for some users and *will* break for us, eventually.
It's more than a bit annoying working with the review process, but we do what we can to stay on top of things and keep everyone aware. We do have many apps that we have setup to test with to try and get a feel for which way the tide is going (is this a good change or a bad one?), but even then, we miss things coming down the pike. One of our best resources is our users to report problems they encounter so we can investigate more. While we have tens of apps to test with, our user base is in the thousands, which is a much better sample size.
I hope that helps explain. Please don't hesitate to ask any questions, report any issues or provide any feedback!
Thanks,
Alex
Facebook app review
