Updated: Apple created a stir early this year by changing the rules for in-app purchases that in effect made eReader apps unable to deal directly with competing bookstores to bypass Apple's 30 percent tax on such purchases. Booksellers were quick to point out that ebooks don't have that kind of margin available to give to Apple, and that changes would have to be made to get around it. The companies behind eReader apps for the iPad and iPhone must have been told the new rules were finally to be enforced, and major changes were noticed this weekend by The Digital Reader that include the removal of Google Books from the iTunes App Store.

There is no official word from Google why the app has been removed, but TDR also noticed that most other eReader apps have been altered to deal with Apple's charges. Nook Kids no longer has a link in the app to buy books from the Barnes & Noble bookstore. This will likely by followed with the main Nook eReader app getting updated soon. The Kobo and Borders apps have already been modified to handle Apple's rules. What remains to be seen is how Amazon handles the Kindle app, which hasn't been modified to date.

These apps no longer allow users to set up new ebook accounts for these stores within the apps, turning them into readers for existing store customers only. This is the way companies are dealing with the in-app 30 percent rule from Apple.

Update: Since publication Amazon has released an updated Kindle app for iOS that "removes the Kindle Store button from the app". The new Kindle app for iOS adds support for magazines and newspapers. Amazon points out that it is still possible to buy Kindle content through Safari or any browser. I guess developers considering moving to HTML5 and dropping the app form entirely may have better reason now.

[via The Digital Reader]