Facebook announced yesterday messaging /Facebook email allows to user to talk to his friends via SMS,Chat, email or messages. Facebook also providing @facebook.com email address for whoever wants one. Facebook says message is not email, you can send email to everyone whether they are using Gmail, Yahoo mail, or Hotmail, and they don’t need be to using Facebook to receive this message.
Much like Gmail priority inbox the important messages will be in inbox. For example messages from your friends and their friends will reach inbox, other messages will go to other folder where you can look at them separately.
Facebook says their email addresses and Messages will be available to everyone over next few months.
You can request Facebook email invite here.