Amazon has an Android Appstore to compete with Google's Android Market, and according to The Loop they've just released a Mac Download Store to compete with Apple's Mac App Store, so how long until they decide they want to be in the iPhone, iPad, and iPod touch space and try to buy Cydia, introduce a Jailbreak app store alternative all their own, or try some fancy HTML5 web app store?
iOS is theoretically a closed garden, yet Jailbreak and HTML5 apps are both alternatives, the letter even officially supported by Apple. Cydia has shown there can be commercial alternatives. Google has shown there can be great web apps. Playboy has shown there can even be subscriptions outside the app store.
Amazon is starting to feel their strength and, like when they launched CloudLocker without label support, they're getting less shy about showing it. Their international support isn't great compared to Apple's, but if they fix that most of the other pieces are already in place.
Would Amazon buy Cydia? I doubt it. But iOS is far too lucrative a market for Amazon not to be considering attacking it in some way.