• There's support for downloading additional content from within an app, rather than having to download a whole new app entirely. That means new levels, new cities for guidebook apps, and that kind of thing can all be sold or given away within the apps themselves. Kindle store is licking their lips.
• Developers set the prices for add-ons, and Apple takes the same 30% cut. It's only for paid apps—free apps can't charge for content.
• There's also a subscription model available, meaning magazines and periodicals can sell one paid app then push out regular updates