Normally, this API access is open and does not require permission. That is, unless some entity wants to access it a lot. In that case, Facebook requires an agreement for reasons primarily centered on protection of Facebook user data and, of course, infrastructure impact.
It’s hard to blame Facebook here. When Apple brags about having 160 million users, with credit card number on file, and decides to sic all of them (and simultaneously) on a Facebook app that will harvest the social network which Facebook took pains to cultivate for years (and for no other purpose than the harvesting itself — unlike, say, Zynga games which bring a lot of page views back to Facebook), you can’t quite fault Facebook for wanting to get some kind of compensation. Apple isn’t building something on top of the Facebook platform here, they’re trying to piggyback and supplant it.
It’s also easy to imagine Steve Jobs deciding — at the last moment, after long, failed negotiations — that Apple is big enough not to need Facebook at all, that it can just as well construct its social graph from scratch. Because that’s how much Steve Jobs and Apple know about social networking: not very.
If Apple is serious about Ping — and they should be, since music recommendations with inline preview have the potential to push a good deal of product — I wager that they’re the ones who will have to give in. Sure, people are signing up for Ping, but if my “entourage”’s experience is any indication, they’re not making a lot of friendship connections and, on Ping more than anywhere, the social graph is where the money’s at.