Facebook is creating a messaging and mail product that is expected to be the next generation messaging system just like facebook itself.in reference to:
"Facebook is completely rewriting their messaging product and is preparing to launch a fully featured webmail product in its place, according to a source with knowledge of the product. Internally it’s known as Project Titan. Or, unofficially and perhaps over-enthusiastically, the Gmail killer"
- Facebook's Project Titan: A Full Featured Webmail Product (view on Google Sidewiki)