Today Amazon launched an HTML5 browser version of its market leading eReader application, Kindle. Called Kindle Cloud Reader, it's a direct response to the 30% cut of sales that Apple now takes from in-app purchases and subscriptions via iOS apps. The 30% Apple toll hits businesses like Amazon hard, because the margins on book sales are slim enough as it is.
The HTML5 Kindle site appears to be optimized for the iPad. It's accessed from the Safari browser in the iPad, so it routes around Apple's App Store. That means Amazon doesn't need to give Apple 30% of an eBook sale. Because the HTML5 site is very close to the functionality of the iPad Kindle app, this is going to have huge ramifications for Apple. Yes, Apple's walled garden has just been structurally weakened. I'd go as far as to say that it's a matter of months, not years, before Amazon pulls its iOS Kindle app from the App Store.