No Surprise: Apple wants to have the only eBook app on the iPad.

The news over the weekend was that Apple is finally enforcing the June 30th cut-off date from their resolution to remove all other external-linking retailers from the app store. Kobo and the Wall Street Journal (subscriptions to the WSJ app were externally linked) both took down their apps from the Apple store and now it appears the Google eBookstore is doing the same. Darrell Etherington reports via Reuters:

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 has been recently updated, and the links to their respective online stores are now absent from the app.

Many commentators, including Etherington who writes for GigaOM, hoped that Apple would not enforce the new guidelines. Hope apparently was not what Apple had in mind when creating the limitation.

Until late in the day, that left only one major external entity in the Apple app store: Amazon’s Kindle for iOS was still present in Apple’s store and continued to link out to the Amazon website for sales. Etherington speculated that Amazon’s commanding market share gave them a unique bargaining position with Apple and he thought that, potentially, they could remain, despite the departure of the other tech giants. Of course, there is no love lost between Google and Apple, and though Google could fold-up Amazon and put it in its pocket, the internet retailer is light-years ahead of the both Apple and Google when it comes to selling eBooks.

Regardless, by day’s end Amazon had capitulated, too, as a late-breaking Wall Street Journal report details. The lesson? Exclusivity has been the name of this game since day one, and no one does that better than Apple.