…the product of 15 months of intensive work within Facebook dubbed “Project Titan,” has received intensive attention in the tech media in recent days based on the speculation that it would in one fell swoop eclipse the world’s largest e-mail networks — Microsoft Hotmail’s 361 million users, Yahoo Mail’s 273 million users or Google Gmail’s 193 million users…...read more..
In true FB style here is the announcement : See the Messages that Matter