The news of Facebook launching its much awaited email service was a viral and has been listed in many popular news sources; but none could explain how to get registered for it. Some sources confirmed that the email service can be activated only by being invited by someone else. And its true!. 
Here is the link to request for invitation to use Facebook’s email service:
http://www.facebook.com/about/messages/
I have already requested for the invitation but to be frank, i am not sure when my request will be approved. As you can see, after requesting for the invitation, the button says ‘You will receive an invitation soon’.
