Following months of rumor mongering and speculation, it would seem that one of the headline new features of iOS 6 indeed is system-wide Facebook integration, TechCrunch has learned from sources. This capability will reportedly work as seamlessly as Twitter integration in iOS 5.
You'll simply provide your Facebook account credentials in Settings and then approve apps to automatically use your account when needed. The report jives with news of apps, not the OS itself, being the focus of iOS 6 that iDB broke today.
As our credible source with deep connections at Apple pointed out, big stuff is expected in stock apps across the board as Apple has apparently re-written them from the ground up to take advantage of new iOS features.
At this point, there's no reason to doubt that Facebook sharing will be rolled out across Apple's apps in iOS 6,, much like Twitter comes enabled in Safari, YouTube, Maps and so forth...