iPhone OS 4.0 Adding Deep Facebook Integration?

It looks like your iPhone could be about to get a whole lot more social by including deep integration with Facebook.

Code in the developer version of iPhone OS 4.0 seems to point to users being able to add a Facebook account at OS level.  This would mean, potentially, that Facebook contacts could sync with your address book (including their profile pictures), messages with your email client and much more.

Other mobile interfaces such as Android 2.0 and HTC Sense already offer this feature and it’s a great way of keeping up to date with friends.  Facebook statuses appear alongside friends’ contact details in the address book and their profile pictures are synced up regularly, meaning you always have an up-to-date picture of your friends.

A more social contacts list would certainly bring the iPhone in line with its rivals. While the initial source of the information about the code is, bizarrely, a nailgun safety blog, the slightly more reputable Engadget has done some digging that backs up the claim and even indicates that Apple could take the idea further with an open framework for Twitter and other social services being integrated in the future.

iPhone OS 4.0 opens up to the public this summer, so there’s not long to wait to find out how much truth there is in all of this.