It's a tale as old as the iPhone itself. Kid picks up parent's iPhone, kid plays game, kid accidentally buys a ton of in-app junk without their parent's knowledge. Parent goes bananas, complains to Apple.
Those complaints got too loud to ignore for Apple, so in February it agreed to a large settlement. That settlement is now live, via a special website Apple have launched, where parents making small claims can opt for either iTunes credit or, in cases where the amount claimed was over $30, cash.
Apple aren't handing out money for nothing; parents will need to prove their kids made the purchases without their knowledge, and only games listed as "qualified" apps will be covered (though that list appears to cover all the main culprits, like Smurf's Village and Angry Birds).