Facebook updated its Messenger iPhone app to bring iOS 6 and iPhone 5 support. The company redesigned the app's conversation window and now looks much like the one on Android, and it looks much better, specially with in-line photos.
Now throughout the app you can swipe left to see who's online and on the main window you have a new compose icon on the bottom right. You can now add those friends you message most to your Favorites.
Facebook Messenger is available for free in the App Store [iTunes Link].