Did You Buy The GameStore App? Apple Offering Refund

"A strange Apple-built iOS app called GameStore appeared and then quickly disappeared in the App Store last week. After its disappearance, we picked the app apart and determined that GameStore was essentially sample code that demonstrates how to perform in-app purchases."

No worries if you did buy one, Apple is processing refunds and will issue credits to accounts within 5 days. If you don't get your credit, then I'd contact the App Store directly.