I think Sony could probably use the same work-around Amazon appears to be using for its Kindle app: tapping a button to shop for books in the Kindle app opens a browser window allowing you to buy a book on the mobile version of the Amazon.com site. Then when you go back to the app it automatically syncs with your book collection and downloads the book. It makes one wonder what other App store restrictions might be circumvented by clever integration of Native and HTML5 apps.
"The company has told some applications developers, including Sony, that they can no longer sell content, like e-books, within their apps, or let customers have access to purchases they have made outside the App Store."
This is possible, but it's so difficult to enforce that I assume it must be a reporting error. Will the dropbox app prevent me from accessing more than 2GB of my folder? Will they force the Pandora app to keep playing music after 40 hours even if haven't paid for a subscription? Will I now have to buy a separate Netflix plan for my iPad that I buy in iTunes instead of getting that with my regular plan?
The minute you allow any sort of third party authentication systems in an app, it becomes basically impossible to know whether or not someone is using those credentials to buy something on a website somewhere that enables access to more data in your app.
Well, remember Apple has a screening process so they don't have to detect credentials — they can just have the reviewer try buying something.
And they probably only really care about the big content sellers (Amazon, Google, etc.) so they wouldn't have that many apps to enforce it on.
As for the variety of different apps, Apple isn't exactly known for being consistent. I'm sure they could come up with different rules for subscription vs. a la carte downloads.
