We've been waiting for this: Integrated social networking in iPhone, specifically of the Facebook variety—evidence of which has been discovered in iPhone 4.0 system files (via jailbreak), with support for contacts and calendars. [Gunning for Safety via Engadget]
The iPhone can already kinda do this via the facebook app. Although, it only allows you to automatically add photos of facebook contacts and a link to their profile. Hopefully, with support from Apple, the photos will be full sized and we can have the option to import a facebook contact rather than just adding a photo to an already existing one.