We launched our application, announced it to the world, got a flood of users that was apparently "abnormal" and were flagged by their ban bot.
Our app was summarily deleted (without warning or notification). All links to the application were flagged as "abusive". And all data published by users of our application was deleted.
The only reason we discovered this was because we were alerted by our users that the application had disappeared from their bookmarks and that they were unable to access it.
Of course, when we brought this to Facebook's attention they restored the application within a couple of hours. Unfortunately, significant damage had already been done: everything published by our users was (apparently) permanently deleted, our open graph stories and actions were completely deleted, and our subscriptions to the payments apis were deleted.
The particularly insidious one is the deletion of the payments subscription. For the last 12 hours, anyone who has tried to make an in-app purchase has been charged by Facebook but not had their purchase relayed to us for fulfillment.