Facebook iPhone App to replace Contacts List:

Facebook’s web app for the iPhone was cool enough, the native app basically transforms Facebook into a mobile directory with rich information about your friends.

If you’re even semi-serious about using Facebook to keep track of your friends, you may never have to click the “Phone” icon to dial them up. Just hit the Facebook icon and move over to the “Friends” tab. You’ll see all of your Facebook friends laid out, and when you click on their names, their contact info appears in the iPhone’s customary user interface.

Tap a friend’s phone number to call them (or hit their email address to write). The only time this method falls through is when a friend has decided not to enter the requisite contact info into their profile (something unnecessarily cautious, in my opinion, if you’ve set up your privacy settings correctly).

This application has the potential to eliminate the need for two other native iPhone features as well: SMS and Email. The app comes with Facebook Chat baked right in so you can send instant messages to friends who are currently online (either at their computers or on their phones). As soon as Facebook figures out a way to keep you “online” and available for chat even when the app is closed - and hooks Chat to the new push notification service so you’re aware of messages as they come in.

Source Article:
http://www.techcrunch.com/2008/07/10/facebooks-iphone-app-almost-replaces-my-contacts-list/