Amazon has launched a new web interface for its Kindle store, completely bypassing Apple's in-app purchasing system for items that are bought through App Store apps.
The original Kindle app for iOS included links to its own Kindle web store. Apple took offence to this move by Amazon, leading to Amazon removing the links for fear of having the entire app pulled from the App Store for violating Apple's guidelines. From that point on, anyone wanting to buy Kindle books on an iOS device had to reach the store manually, with no mention of it inside the Kindle app.