Microsoft took this situation very seriously and put the site down for now, the hackers placed a picture of the Guy Fawkes mask that is often used by Anonymous hacker group who are known for their high profile hacking activities.
Many sources claim that hackers had access to the database and a list of usernames and passwords have been released. But the shame is that Microsoft saved user accounts password in plain text format.
Today Microsoft has sent email to users, requesting to change their passwords immediately."
Link to Original Source