According to the WSJ, Mike Serbinis, Kobo's chief executive, said Apple told Kobo Saturday that it could no longer operate its digital bookstore from its Kobo apps and had to stop selling e-books directly through them. Kobo subsequently altered the apps so that they no longer sell digital titles.
The WSJ, who themselves were circumventing Apple's payment system by providing links to their website from inside the iPad app, will soon remove all purchasing options from their app.
"We remain concerned that Apple's own subscription [rules] would create a poor experience for our readers, who would not be able to directly manage their WSJ account or to easily access our content across multiple platforms," a Journal spokeswoman said.
Earlier today, Amazon also released an update to their Kindle application to remove the button that takes users to the online Kindle Store.