The NYT reports that Apple "has told some applications developers, including Sony, that they can no longer sell content, like e-books, within their apps, or let customers have access to purchases they have made outside the App Store.
Apple rejected Sony’s iPhone application, which would have let people buy and read e-books bought from the Sony Reader Store...The move could affect companies like Amazon.com and others that sell e-book readers that compete with Apple’s iPad tablet and offer free mobile apps so customers can read their e-book purchases on other devices. An iPad owner, for instance, has not needed to own a Kindle to read Kindle books bought from Amazon.
That may now change."
No word yet on whether this will affect the Kindle app, but it seems ominous. Glad I didn't buy an iPad...