This Wall Street Journal article
offers some predictions for credit cards in 2011. One of the predictions is more cash-back promotions. It cited a study which described the benefits that credit card issuers get from cash-back cards:
With an average cash-back reward of $25, consumers spend about $79 more a month on the credit card, researchers found. At the same time, they raise their debt level by $191 a month because their average monthly payments fall, too.