Nefarious hackers have figured out how to boost Microsoft Points. Earlier today, word came from the less savory corners of the internet that the string of numbers on the back of those "Get 1600 Microsoft Points!" cards can be cracked, and once you figure out which numbers to enter, you can give yourself free points. Reportedly, over a million dollars worth of points have already been jacked.
Crime, as you know, doesn't pay, unless you do it really quickly. Microsoft was onto the scheme hours after it began, and have taken steps to shut down to the exploiters, issuing a statement saying, "We are aware of the situation and have taken steps to invalidate the codes obtained illegitimately." Microsoft also says it was a lot less money.
Because Microsoft can track which card numbers are invalid, they say they'll be able to take back their precious, precious fake currency. Although not explicitly stated, I can only assume M'Soft will un-download anything downloaded with the purloined points.
Oh, and if you have a string of numbers that you think will give you some points, I wouldn't enter it. It likely won't work, and what are you, some kind of criminal?!