I don't engage in a lot of the quizzes and random stuff on FB, but when Alyssa Jenkins "hit me with a pillow" I went ahead and added the app and "hit her back." Over the next few days we hit each other with various pillows -- she'd hit me with the Luxury Pillow, I'd hit her with the Leather Pillow. Each time we hit the other, the Pillow Fight app would post the photo of the pillow being used to our respective walls and send a note to the person getting hit saying "you've got 2 days to hit back or you lose!"
With two days to hit back (an eternity for someone online as much as I am), the game could go on forever, which wouldn't be a problem until I got a roadblock that if I didn't grant them constant access to my account (meaning they could post whatever they wanted whenever they wanted) AND give them my real email address, not the FaceBook proxy, or else I wouldn't be able to hit Alyssa back.
I conceded the fight and deleted the app.
Normally this would be the end of the story, but after rating the app 1 out of 5 stars, one of the Pillow Fight developers sent me a note (because of my comment and previous use of the game, the Facebook app allows him to send a message via the Facebook messaging system) and he gave me some background.
First was the link to the FB Developers blog Communicating Directly with Your Users via Email explaining that Facebook is encouraging developers to communicate directly with users rather than using the FB messaging system. Second was a link to the developers roadmap wiki showing that Facebook will actually be taking away the current notification functionality.
Not only that, but there seems to be a bug in the FB API which creates a loop, that is to say, I can't get out of the "give us your email" messages and play the game, because FB doesn't give the programmers a way to get out of it.
Facebook is a tricky place to write applications -- you have to create most of your programming on your own servers but interact with custom code that Facebook keeps changing. The Pillow Fight guys seem sincere in trying to provide a fun game, and while they have the aesthetics of programmers (which means their interface isn't exactly a work of art), I know the frustration of having to write code and rewrite code based on events outside your control.
Of course, this is one of those themes I keep getting back to -- when your business model is completely dependent on one company, be it Facebook, Apple, or the coal mine, you're going to get screwed. Your interests are not the same as the big corporation you're playing with, and all it takes is a casual flick of a corporate finger somewhere to accidentally kill you.