Liz Gannes writesfor All Things D that Apple’s social integration in iOS 5 includes much more than Twitter, which was formally announced during the WWDC 2011 keynote on Monday. Look no further than contact cards in a developer version of iOS 5, Gannes writes:

In addition to four additional social networks, iOS 5 contact cards also include an option to add custom service by pasting a profile URL.

Of course, this little discovery in no way means that the final version of iOS 5, which ships this fall, will support other social networks as Apple may have provided said hooks simply to eventually enable greater social integration in iOS down the road. It is also possible that these fields are just what they appear to be, the place to provide links to your contacts’ profiles on popular social networks. It makes sense not to stop at Twitter integration, however, especially given the popularity of other social networks and the fact that social streams are being integrated in rival mobile operating systems.

Update: A developer writes in :

More on Facebook, Flickr etc. in iOS 5: Apple is prepared for other social network integrations in iOS. There is a so called Accounts framework in iOS 5. It\’s made to store credentials for social networks in general and is currently used for the Twitter integration only. Apple could easily extend the framework for other social networks.

\”The Accounts framework (Accounts.framework) provides a single sign-on model for certain user accounts. Single sign-on improves the user experience, because applications no longer need to prompt a user separately for login information related to an account. It also simplifies the development model for you by managing the account authorization process for your application. In iOS 5.0, applications can use this framework in conjunction with the Twitter framework to access a user’s Twitter account.