Google Books says goodbye to Apple App Store

Update: The Google Books app is now back in the App Store, after making changes that put it in line with Apple’s newly-enforced rules. Amazon has also updated its Kindle app and removed the link to its store, which means it, too, is playing nice with the revised App Store guidelines.

Many, myself included, were hoping that Apple’s (s aapl) implementation of new rules that prevent e-book retailers from linking out to their own storefronts had permanently fallen by the wayside when they didn’t immediately go into effect after the original June 30 cutoff date. Unfortunately, events this past weekend proved that may not be the case.

The biggest development is that Google Books (s goog) is no longer available on the App Store. The app, introduced in December of last year, allows users to read books from Google’s e-book service. It also provides access to the web-based Google eBooks store, which is against Apple’s new rules. The banning of outside links seems designed to prevent e-book resellers from bypassing Apple’s own in-app purchase mechanism, from which Apple garners a 30 percent cut of revenue.

While Google hasn’t yet confirmed that the rule change is the reason for the app’s removal (we’ve contacted them and will let you know if they do provide comment), given changes that have taken place in other e-book apps in recent days, it seems very likely. E-reader software from Kobo and Barnes & Noble (s bks) has been recently updated, and the links to their respective online stores are now absent from the app.

The last major holdout is Amazon,(s amzn) which still hasn’t issued a change for its Kindle app. Kindle for iOS still prominently displays a button that links out to the Kindle store on the web. Amazon is arguably the only e-book retailer in a strong-enough position to be able to negotiate with Apple regarding the new rules for e-book stores, since it reaches a very large audience through its presence on virtually every platform. Amazon is also known to be working on its own tablet device, which could give it even more bargaining power. Barnes & Noble and Kobo would likely stand to gain a lot if Amazon decides to leave the Apple ecosystem and go it alone, since users who decide to stick with iOS will need a replacement e-book resource.

As a Kindle user and iOS-device owner, I’m hoping that we see a solution that allows the Kindle app to remain in the App Store. But as an industry observer, I’d be very interested to see who would fare better if users are forced to choose between Amazon’s better e-reader software and library, or Apple hardware. Anyone care to place any early bets?