Not wishing to spread fear but...
In the past hour or two, there have been two cases (that I know of) of people losing their hotmail/messenger accounts to a hacking group calling themselves the K.S.A.
Affected accounts normally have their display name changed to something similar to: “Hacked By K.S.A.”
I don't know how many more accounts this may happen to, and I hope it is none.
Personally, I would advise that people set really strong passwords, keep their passwords safe and watch out for anything unusual.