Was Apple's Cards service discontinued?
Apple discontinued its Cards iOS app service on September 10, 2013. The official Apple Cards: Frequently asked questions page states:
As of September 10, 2013, the Cards iOS app service is no longer available.
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.
Note: You can still order beautiful letterpress cards customized with your photos and text using iPhoto on your Mac. Cards ordered through iPhoto are shipped through a carrier such as FedEx rather than through the United States Post Office.