Why no Facebook Deep Integration in iOS 5?

Don Reisinger over at Cnet offers a detailed look into why Facebook has been given the cold shoulder in iOS 5 while Twitter has seen much love from Apple.  A few things he points are that the companies are just too different.  Also maybe Apple knows that people have Facebook overload and would not appreciate it sticking its face in your face from every app.  Whatever the difference is, Apple has turned it’s back on one of the largest user bases in history of social networks.