After its debut in beta form in last July, Microsoft has officially launched Outlook.com as its new flagship email service. At the same time, the Redmond-based software giant also revealed that since it was first unveiled, the service has grown from zero to over 60 million users in the past six months. Beginning today, Microsoft says that Hotmail users will be automatically upgraded to the new Outlook.com service, while still being able to retain their original Hotmail.com email address.