Tweet to buy: you can now shop on Twitter with American Express

Twitter just became a mall. Thanks to a new partnership between Twitter and American Express, the humble hashtag now has yet another purpose: ecommerce.

The social network teamed up with the US financial company to unveil a new service which allows eligible cardholders to sync their Twitter accounts with their card. Customers will then be able to see special product promotions from Amex in their feed, and signal their interest by tweeting with the designated hashtag. The @AmexSync account will then @mention them, informing them they have 15 minutes to confirm the payment by responding with the hashtag again. One more tweet from the cardholder, and it’s all over: they’ve shopped on Twitter.

If full-scale Twitter shopping is a step too far, customers will also be able to use the service to redeem special offers in the same way — but instead of confirming a payment, the offer will be linked with their card and activate if they hit the physical store to buy the item before an agreed-upon cancellation date. No coupons or print outs needed — their account will simply be credited with the savings.

Granted, it’s not exactly a free-for-all megastore at the moment: there are only a selected number of specials and products available (Amex giftcards and items from Amazon, Sony and Xbox are some of the first to be offered), and not all types of cardholders will be able to use the service. While Twitter has declined to disclose how it is profiting from the deal, it could be an interesting new source of revenue for Twitter if it takes a cut from the sales of each product. As the Wall Street Journal points out, partnerships like these could be a potential saving grace for marketing execs trying to ensure that a tweet really does equal some tangible benefit, like a sale of their product.