I kind of lump this kind of in-game marketing to children into the same category as what happened in the 80's with the 900 phone numbers that racked up enormous phone bills for parents with their kids calling their favorite cartoon characters and Santa Clause for $2.00/minute auto-billed to their phone bill.
The phone companies instituted a voluntary block that parents could apply to their accounts to block anyone from calling 900 numbers, and soon after, there was a law passed that made it illegal to market 900 numbers (and other similar auto-charge things) to kids.
With this example, and the resulting laws that were enacted, Apple may be in some really hot water with this, or at the very least, the app developers that are deliberately marketing the auto-billed stuff to kids.