Facebook have launched a new messaging system that includes SMS, and it will eventually be available to all members, although at the moment it’s being rolled out slowly.
Shortly, from Facebook’s Social Inbox, you will be able to send email, chat, Facebook messages and SMS to other Facebook members. Every member will have access to their own Facebook email address: @facebook.com.
One of the main advantages could be the lack of spam within the Facebook system, but also the ability to send messages from any device as long as you have an internet connection.
At the moment the new service is invite only, but gradually more and more people will get access.