It's not anything new that iTunes has been susceptible to hackers from the beginning: with it's poorly trained help desk, full credit card accessibility, and Apple's "[lack of responsibility] for In App purchases;" however, lately Apple has been getting a lot of calls regarding this matter. Accourding to one user
I was hacked today for almost $50 in Apple gift card money. First someone gained access to my account and 'downloaded' the free Kingdom Conquest app at 2:45 a.m. when I was asleep, and then bought almost $50 worth of In App Purchases from SEGA Corporation. SEGA says I should complain to Apple and ask for a refund. 
CNET reports that a few users have gotten refunds; albeit, Apple is yet to fix it. Ty Miller told Apple insider he thought it might be more cost effective for Apple to hand out refunds, than fix the system.