The release today of the developer preview version of Windows Phone 8.1 doesn't include everything that will be put into the final release of the mobile OS, such as the lock screen themes app. However, it does include one unexpected addition: support for the Passbook mobile payment system that Apple developed for its iOS devices.
Passbook officially launched in 2012 when Apple released iOS 6. It uses bar codes to store coupons, tickets and boarding passes, among other things. The Verge's Tom Warren first posted up word that Windows Phone 8.1 supported Passbook on his Twitter account. According to WPCentral, Microsoft has taken the same Passbook data used to make a card on iOS devices and modified it to create the same card on a Windows Phone 8.1 smartphone via Microsoft Wallet.
While Passbook may work in the developer preview version of Windows Phone 8.1, it's not clear yet if Microsoft and Apple have worked together to add this feature or if Microsoft has put in Passbook support on its own, without the knowledge or approval from Apple. We have contacted both companies to see if they wish to comment on this matter.