Finally facebook is holding an event right now, you can see it live here. As it seems facebook is releasing new messaging service which will have following key features like seamless messaging, conversation history and social inbox.
The most important thing about facebook messaging is that it is not email messaging rather it will be social inbox which will help you filter messages. Facebook messaging can also be used using the iphone app, it will have conversation history of messages received or sent to friend on facebook. With new Messages, your Inbox will only contain messages from your friends and their friends. All other messages will go into an Other folder where you can look at them separately.
Another thing to notice about messaging / email will be invite based, so you will not able to access it until someone invites you. Facebook messaging will support imap protocol so you can fetch facebook email messages. With new facebook messages you can also change your account settings to be even more limited and bounce any emails that aren’t exclusively from friends.
Facebook new messages tour is going to be live at http://www.facebook.com/about/messages/ – However the page does not seem to be live yet
[ Source – Facebook Blog ]