This is a big reminder to all devs, make facebook an optional part of your application and that it can stand alone by itself if facebook gets revoked. Even if

This is a big reminder to all devs, make facebook an optional part of your application and that it can stand alone by itself if facebook gets revoked. Even if you make it seamless don't make it depend on facebook internally, make it that you can flip a switch and send an announcement email/sms to all of your users that provide it. I was surprised how many facebook apps start completely dependent like this and stay like that for years.