Recently Facebook introduced a new feature for its users and it is Facebook Messaging. This service allows FB users to manage Emails, Chats and SMSs under one account.
Currently this feature is available to those who get an invitation from the Facebook. To get an invitation visit this page and click on “Request” button after logging in. You will receive an invitation to Facebook Messaging (Email) soon.
Setup is simple on the web. You get an invitation, you accept, then you get your @facebook email address, verify your SMS number (if you want), and login to chat (also if you want). After that you’re hit with the new interface. Once that’s setup, the next time you launch Facebook on iPhone you’re alerted that new-style messages are available (same way Places alerted you when it arrived) and you’re good to go.
Until you receive the invitation and enjoy the service yourself, check out the screenshots of new Facebook Messaging on iPhone.