"We are now requiring that if an app offers customers the ability to purchase books outside of the app, that the same option is also available to customers from within the app with in-app purchase."
It's talking about purchasing from inside the app, not access content that you purchased somewhere else.
Not quite. Another way of describing this; if the content is available for sale outside of the app .. it can't be accessed within the app, unless it's also available for sale via Apple's store.
"...if an app offers customers the ability to purchase books outside of the app, that the same option is also available to customers from within the app.."
It says if the app lets you purchase books from somewhere that is not the app, the app should also let users purchase through the app. Apple said nothing about "content...can't be accessed within the app, unless it's also available for sale via Apples store." There was nothing said about what content can and can't be accessed.
1) All possible electronic commerce is likely to utilise web-based technologies.
2) In Amazon's case, they used a mobile website to allow sale of their e-books.
3) If Apple is going to state that directing the user to a mobile website to purchase a book, constitutes an 'in-app purchase' - where is the line drawn?
4) Will app developers be able to advertise any alternative methods of purchase, within their apps, without also allowing purchase via the Appstore?
My guess is, no; they'll simply deny the app in question access to the marketplace - which will prevent users from viewing any externally bought content, that can't also be bought via the Appstore.
In-effect Apple are holding these developers over a barrel.
"We are now requiring that if an app offers customers the ability to purchase books outside of the app, that the same option is also available to customers from within the app with in-app purchase."
It's talking about purchasing from inside the app, not access content that you purchased somewhere else.