Actually, it's a refund for people from the state of Iowa, in the USA.
I know this is a BR website, but I thought that since MS is competition, it would be interesting to some folks around here:
http://www.usatoday.com/tech/product...owa-case_x.htm
You can claim up to $200 back, depending on how many copies of Windows, Office, etc., you purchased between 1996 and June of last year. If you claim over $200, then you have to provide proof of purchase. The first $200 worth doesn't require any proof.