Loyalty cards are all the rage these days. Not only do cost-conscious consumers like to save a buck or two, especially in tough economic times, but the customer data they can generate turns out to be a very useful thing for companies to have. Today, Dunkin’ Donuts said it would get in on the action, launching its own loyalty program later this year. Competitors like Starbucks and Panera Bread have reported significant sales boots from their own programs, and Dunkin’ has already released a mobile app that lets customers pay using their smartphones.