It's becoming a classic cautionary tale: A busy British woman punched in her passcode so her 5-year-old son could download a free game. Within fifteen minutes, the toddler had spent over £1,500 (around $2,200) on in-app purchases.
Many apps -- both paid and free -- offer in-app purchases these days. The most common strategy is to offer app currency through an in-app purchase, and some of these currency packages can be quite expensive. This means it doesn't take much time to for a toddler to spend a lot of money inside of an app.
Luckily, Apple refunded the money in this case. They've been pretty good about refunding charges when a child builds up a huge bill. But rather than depend on Apple, parents should make sure their iPad is kid-safe by turning off in-app purchases in the iPad settings.