This weekend at SXSW in Austin, Facebook’s Dave Morin announced the launch of Facebook Connect for iPhone. Now, iPhone app developers can integrate Facebook Connect natively into their apps so users can easily connect and share game content with their Facebook friends from inside the app. Facebook Connect for iPhone is a big step forward in the advancement of the social web because it bridges the social graph, identity, and privacy of Facebook with the rich, mobile application platform of the iPhone for the first time.

However, unlike some may think, Connect for iPhone doesn’t just create new opportunities for Facebook application developers to expand their reach to the iPhone (though it certainly does that too – companies that were large on Facebook before the iPhone like Flixster, SGN, Zynga, and Playfish are already showing the power of a cross platform mobile and social app ecosystem with the strategies behind their iPhone Facebook Connect integrations they launched this weekend).

Rather, it also offers significant new opportunities for iPhone app developers to create new kinds of engaging social interactions and powerful viral growth by connecting their applications to Facebook’s social graph and feed system for the first time. We’re going to see lots of interesting new and improved applications coming from iPhone app developers in the upcoming weeks and months that take advantage of both the social graph to create more compelling experiences and the power of the News Feed and invitations to create more powerful viral loops.

Take Urbanspoon for example, of the highest rated restaurant review applications on the iPhone that announced Facebook Connect integration this weekend. Urbanspoon has already added a “Friends” feature that lets users share their ratings with Facebook friends and see what their friends have done on Urbanspoon lately. The potential for this type of interaction to become very engaging and viral is quite high – especially as Facebook adds more support for all the communication channels on the iPhone that Facebook Platform application developers have been using for some time.

We’re only at the beginning, but Facebook has opened the door for iPhone app developers to create some seriously social mobile applications. Which iPhone developers take advantage of these opportunities most quickly will be interesting to see.