I guess with all of the money flowing around iTunes, sooner or later someone would have to try to steal some of it. Twelve people have been charged in the UK with basically laundering money through iTunes -- they were allegedly uploading their own tracks onto the music sales service, then buying those same tracks with stolen credit card numbers. The fraudsters nabbed over $300,000 worth of royalties in just a four month period between September 2008 and January 2009.
The Register doesn't note how the 12 (who come from a surprising number of various jobs and backgrounds) came up with this idea, or how they got caught, although there was an investigation underway by the FBI. iTunes wasn't the only service defrauded -- Amazon was reportedly used for some of the transactions as well.
The suspects are scheduled to appear on bail next month, and I'm sure both Apple and Amazon have taken steps to make sure this doesn't happen again. Even so, out of all of the millions if not billions of dollars running through iTunes, if this $300,000 is all of the theft they need to worry about, Apple's doing pretty well anyway.