We’ve received multiple tips indicating that Apple’s Cards app and service for iOS has stopped functioning. Cards was launched alongside the iPhone 4s in fall 2011 and served as an easy way for users to create custom-made letterpress cards and have them shipped to another person.
Apple has confirmed that Cards has been discontinued as of today:
Cards ordered before 1 PM Pacific time on September 10, 2013, will be delivered, and push notifications will continue to work. You can view your previous purchases by tapping Saved Cards in the app.
As a replacement, Apple recommends creating letterpress cards on iPhoto for Mac. Thanks, Zac Coffman!