1. They started a year ago (at SXSW) with Foursquare check in deals/rewards loaded as cash back on card purchases when you check-in at Amex merchants - https://sync.americanexpress.com/foursquare/ 2. Then it was Shopping rewards on Facebook based on your social graph that is loaded into your card (Link-Like-Love and Go Social): http://techcrunch.com/2011/07/18/amex-facebook-deals-go-social/ ) 3. Now they reward you when you tweet with a specific Amex hashtag (again offers loaded back to your card): http://www.fastcompany.com/1823041/the-social-credit-card-amex-syncs-with-twitter-to-turn-hashtags-into-savings
Amex completes the Social Media trinity.
All 3 initiatives above are social by design and the customer's credit card is electronically linked to their respective Foursquare/Facebook/Twitter accounts, making it instantly socialable and allowing Amex to track if these deals eventually activate and increase card spending.