As part of the launch of The Daily yesterday, Apple updated the T&C for iTunes. It looks like they're going after a cut of all the money, not just the single issue sales. To be fair, I'm not all that upset by this change. These terms really aren't all that unreasonable.
They've now spelled out how subscriptions sold through the app store will work, and I don't see anything you wouldn't expect. Apple will automatically collect the subscription payment less than 24 hours before it's due, but won' t charge you if the price went up. Apple will also bug you about sharing your email and contact info with the app's publisher.
Here is the relevant change: