@facebook.com “the next evolution of Messages”
“…We are also providing an @facebook.com email address to every person on Facebook who wants one. Now people can share with friends over email, whether they’re on Facebook or not. To be clear, Messages is not email. There are no subject lines, no cc, no bcc, and you can send a message by hitting the Enter key…”
For more, see this http://blog.facebook.com/blog.php?post=452288242130