This may be unrelated, but yesterday I noticed that my iTunes account had became corrupted with someone else's data. My first name, last name, address and registered CC number became someone else's info. Had I not noticed, I would have been making charges against this other persons account.
Maybe someone wrote one messed up database query and screwed up a massive amount of people's payment association. Some users are starting to notice they have someone else's info and are going on a buying spree. Or people are just making their normal purchases and are unknowingly charging other people's accounts, like I almost did last night.