How will I know when Facebook is going to push new code to its production servers? What if it breaks my app?!
Facebook generally does one weekly push of new code to their production servers, which is currently scheduled for Tuesdays. The details of the push (which is, essentially, the list of check-ins to Facebook’s source control server) are available from the Wiki’s Push Changes page at http://wiki.developers.facebook.com/index.php/Category:Push_Changes.
If you’re actively working on a new app or maintaining an existing one, you should make sure to test it on Wednesdays to see whether the push has broken anything for you. But don’t fixate on that day of the week, as Facebook sometimes moves the actual push day to Monday. You can see when the push is scheduled by keeping up with the Platform Status Feed from the Developer app, which you can find at http://www.facebook.com/developers/message.php?id=233, or you can subscribe to it by RSS/Atom at http://www.facebook.com/feeds/api_messages.php.
As of mid-May 2008, Facebook has started pushing its release candidates to http://www.beta.facebook.com on the Monday prior to the Tuesday push to production, so that developers can test and report bugs. You should definitely take advantage of that testing window, so schedule some blocked-off time on Monday nights to make sure your babies haven’t broken.