The feature will work similar to the web based version. Any iPhone app with Facebook connect integration will let you login with your Facebook account and make it a breeze to find and connect to your Facebook friends. You will also of course be able to share your actions with your Facebook friends.
Interestingly, you will also be able to keep the same privacy settings that you have set on Facebook.com for those particular friends.
According to the Facebook Blog, many more applications featuring the integration will be available in App Store over the coming days.