By Jeffrey A. Trachtenberg And Russell Adams reporting:
>In a pair of moves that suggest Apple Inc. is enforcing rules for selling content on its devices, Kobo Inc., the Canadian e-book retailer, and The Wall Street Journal said Sunday they will no longer sell content directly to customers through their apps for Apple devices.

[I doubt any of this will matter soon.](http://www.apple.com/ios/ios5/features.html#newsstand)

UPDATE: [Looks like Amazon killed their button to the Kindle Store too](http://www.macrumors.com/2011/07/25/amazons-kindle-app-updated-to-remove-direct-kindle-store-links/). Periodicals will likely go the way of the Newsstand as I alluded to above, however book apps like Kobo and Kindle — they will likely have to suffer. Still though it’s better than Apple making iBooks the only ebook reader on iOS.