Amazon.com's Kindle app for iOS devices was a real game changer. For Amazon, it helped to remove the stigma that buying e-books through the Kindle store was tantamount to device lock-in, leaving purchasers forever tied to a Kindle. With the ability to access and read their Kindle books on their iPads, Amazon.com shoppers had an out. And a pretty good one at that. From Apple's perspective, e-reading has been a significant part of the iPad's success. While Apple's own iBooks and iBookstore have been successful, there's no doubt that the Kindle e-book accessibility has been a significant factor in the iPad's popularity as an e-reading platform.
However, the honeymoon appears to be over, and it's all because of these four words: Shop in Kindle Store.
These words make up a prominent link on the home page of Amazon's Kindle app for the iPad and Apple is making noise about shutting it down. Why? Leaving the Kindle app with a direct connection to the Kindle Store means users buy e-books from Amazon.com that they can access while using their iPad, but without Apple getting a cut of the revenue; something that Apple forbids in its terms of service for app developers. To be clear, Apple is okay with a customer launching Safari on their browser, surfing to Amazon.com and buying a Kindle e-book. They probably aren't thrilled with this, since they get no cut of this sale, but since the customer had to leave their Kindle app and conduct the shopping on their own, it's assumed that this scenario is less likely to happen. Buying your Kindle e-books while in the Kindle app is more convenient, so that's the route most people are expected to go —especially with that big, prominent "Shop in Kindle Store" button.
Apple provides an in-app payment system to cover purchases made from within an app used on one of its iOS devices. If any content is purchased using this system, Apple nets 30 percent of the sale. In-app equals revenue for Apple and that means 70 percent less revenue on a Kindle book sale for Amazon. You can see where the tension arises. This in-app purchase rule has been in place for a long time and there was some thought that Apple might blink, but the company did forcibly remove Sony's Reader app from the app store several months ago for the exact same reason. June 30th was the latest deadline for compliance offered by Apple and as of 6pm EST on July 1, the Kindle app is still available in the App Store –and it's still version 2.7, the same non-compliant version.