Apple has provided Twitter integration in iOS 5 and included a framework to allow the company to extend it to account integrations. So, Facebook integration as a system-level feature would not be a stretch. These screens closely resemble those of Twitter's integration and are likely just mock-ups ("addresses" is spelled wrong):
Ultimately, Apple's decision to integrate Facebook into iOS seems to depend on negotiations between the two companies. Apple had closely integrated Facebook into its Ping social service, but the feature was pulled at the last second due to "onerous terms" that Apple could not agree to at the time. Since then, Facebook may be feeling more pressure with the early growth of Google's own social network, Google Plus.