Last year American Express launched its “Amex Sync” integration, where customers could link up their credit cards to Twitter and get discounts on certain items by way of special offers sent out on the social network. And now the two companies are turning hashtags into dollar signs with a joint venture that allows users to buy certain items simply by hashtagging tweets.

While you won’t be able to tweets something like “Can someone please bring me #lunch?” and expect a delivery of all your favorite food items, the partnership will include products like Amex gift cards, Kindle Fire tablets from Amazon and Donna Karan jewelry, reports the Wall Street Journal.

Of course, Amex users will first have to connect their cards to their Twitter accounts first, otherwise those hashtags will remain monetarily worthless.

American Express said the feature “turns Twitter #hashtags into purchases in a unique and seamless way. American Express Cardmembers who sync their eligible Cards at sync.americanexpress.com/twitter and tweet special #hashtags can buy American Express Gift Cards and products from Amazon, Sony, Urban Zen and Xbox 360.”

Twitter and American Express are keeping their lips zipped on the details of their hook-up, but the WSJ says Twitter hasn’t denied it won’t take a cut of e-commerce sales in the future.

“We’re convinced that commerce is going to be one of the areas (for which) advertisers are going to start using our platform,” Joel Lunenfeld, Twitter’s vice president of global brand strategy, said in an interview.

Indeed, this moves companies closer to using Twitter as not only a marketing platform, but a point-of-sale. Engage’em, hook’em, bag’em, all on one social network.

Amex says it will open up its Twitter stores to more merchants eventually, just as it started with 16 companies in its first iteration of the Twitter discount program. It now says hundreds of retailers have signed up since its launch almost a year ago and that hundreds of thousands of card holders are on board as well.

Twitter, Amex to Collaborate on E-Commerce Sales on Twitter [Wall Street Journal]

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