Apple has quietly changed its guidelines on the pricing of In-App Subscriptions on the App Store. There are no longer any requirements that a subscription be the "same price or less than it is offered outside the app". There are no longer any guidelines about price at all. Apple also removed the requirement that external subscriptions must be also offered as an in-app purchase.
via Mac Rumors – Apple Reverses Course On In-App Subscriptions. Good news for publishers and services like Amazon’s Kindle and Netflix.