Earlier this week, Sony complained loudly via a New York Times article that it's eBook reader app had been rejected by Apple because it did not use Apple's in-app purchasing system. That set off a storm of speculation on the Internet about whether Amazon's Kindle app, comic book apps and other apps that sell content outside Apple's ecosystem would soon be pulled from the store. In response to the ruckus, Apple took the somewhat out of character approach of issuing a press release in which it said that it now requires anyone that offers content outside the App Store to also offer it via Apple's in-app purchasing process. John Gruber has a great in-depth post on the entire affair here.
Gruber speculates that Sony is suffering from being late to the game and that Apple is unlikely to impose these seemingly new policies on the likes of Amazon. I think that's more likely right than not, but it will be interesting to see how that and especially how pricing are handled. What is also clear to me is that this is not just a Sony or Amazon issue. I suspect that a number of content providers have been forewarned that they need to implement in-app purchasing based in part on the fact that the Sony dust-up coincided with other content providers contacting developers about implementing in-app purchases.
This will be an interesting battle. While Apple does not seem to be pushing publishers to use in-app purchases exclusively, the practical effect making all of the content available through Apple may lead publishers to become as dependent on Apple as the record labels became.