Public launch September 17 ahead of iPhone 6 debut.
Windows Phone 8.1 Adds Support for Apple's Passbook Passes
As noticed by Tom Warren of The Verge and reported by iMore, Microsoft has created a method that takes the data from a Passbook file and converts it into a card that is imported into Microsoft Wallet.
Windows Phone 8.1 supports Apple's Passbook natively. I've been using it for flights. Works perfectly pic.twitter.com/MFScqvEVU7— Tom Warren (@tomwarren) April 14, 2014