[kenschunk]

Here's what the actual license agreement from Apple says about this...

1 - if you're going to enable in-app purchases they HAVE to use the In App Purchase (IAP) API. This is where Apple gets their 30% cut - sounds like Sony ignored that.
2 - if you use the IAP API, you CAN NOT offer anything that can be used outside of the app on the iOS device. That's probably another reason Sony didn't use the IAP API, since any books purchased would be usable outside of the iPhone/iPad app.
3 - I can't find anything, anywhere, in the license agreement (downloaded on 2/2/2011 from Apple's developer web site) that states if it's available outside of the app (say, as Amazon or B&N does it from a web site) that it has to be available thru the Apple store. There is a section (3.3.3) that states you can't add additional features or functionality without going thru the IAP API, but I would be surprised if documents, such as books, would fall into this category.

The real problem is that Sony didn't play by the rules and got caught and rejected. If Sony had a web based bookstore, like virtually everyone else, they could have done what every other eReader app does and link to that web site.

Of course the really amusing part of this is that one "lock down proprietary" company (Sony) is complaining about another "lock down proprietary" company (Apple).