You decide how you want to talk to your friends: via SMS, chat, email or Messages. They will receive your message through whatever medium or device is convenient for them, and you can both have a conversation in real time. You shouldn't have to remember who prefers IM over email or worry about which technology to use. Simply choose their name and type a message.
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. We modeled it more closely to chat and reduced the number of things you need to do to send a message. We wanted to make this more like a conversation.
In addition to Seamless Messaging Facebook is also introducing:
Messages is built for communicating with your friends, so it made sense to organize primarily around people. All of your messages with someone will be together in one place, whether they are sent over chat, email or SMS. You can see everything you've discussed with each friend as a single conversation.
The Social Inbox
It seems wrong that an email message from your best friend gets sandwiched between a bill and a bank statement. It's not that those other messages aren't important, but one of them is more meaningful. 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.
The new Facebook Messages is being slowly rolled out; however, you can request an invite at the link below...