Hot flash... this has been around a long time. It is particularly common in places like Yahoo Messenger, where messages can be sent to thousands of subscribers simultaneously.
Usully with bait like "Great ______" (fill in the blank.)
They are usually a zip file with 0 files.
Idiots who open these are almost sure to do it just once.
Moral of the story: if you don't know the sender, Don't open it!
I don't. But it would take just that one lapse of thought.