Twitter just announced it’s acquired CardSpring to enable “in-the-moment commerce experiences.” CardSpring is an application platform that lets developers build card-linked offers electronic coupons, loyalty cards, and virtual currencies that work with credit cards and other types of payments. Twitter will keep the service open.

CardSpring writes “At Twitter, we will continue to grow the adoption of our platform and work with our publisher, financial, and retail partners to create new, innovative commerce experiences for consumers.”

Twitter explained that “we’ve already given users the ability to get deals and discounts, surprise someone with a coffee, or even add items to their online shopping cart — all directly from a Tweet. As we work on the future of commerce on Twitter, we’re confident the CardSpring team and the technology they’ve built are a great fit ” For more details on CardSpring, check out our past coverage.

Twitter could use CardSpring to enable card-linked offers. For example, you could get a discount offered in tweet from a merchant that would ask you to enter your credit card number (or perhaps one day pull it from a card you have on fil with Twitter). When you make a purchase at that merchant later, online or offline, CardSpring would recognize your card number and apply the discount. It would then report back to the merchant with analytics on the performance of the offer. These online-to-offline promotions could make Twitter more relevant to local businesses who want to drive brick-and-mortar sales, not just retweets and follows.

Last year CardSpring launched CardSpring Connect, a full-fledged commerce analytics system that jacks into a merchants existing in-store point of sale system. It lets businesses track how their sales are connected to online promotions through services like Foursquare, Trialpay, Thanx, MOGL, Roximity, Moblico, and OnStripe.

CardSpring was founded a few years ago by a group of former Netscape engineers and executives. It had raised over $10M from Greylock Partners, Accel Partners, Morado Venture Partners, SV Angel, Data Collective, John Hering, Felicis Ventures, and Webb Investment Network.

While CardSpring had an impressive array of merchants and developers already working with it, Twitter will give it a powerful way to distribute offers built on its platform.

The acquisition could give Twitter a weapon in the battle to be the web’s social commerce portal. Earlier today Facebook began testing a Buy button that lets ecommerce shoppers make purchases straight from the News Feed. But Twitter may have the edge here for one important reason: the retweet. When people like something on Facebook, they Like it. But on Twitter, they retweet, instantly amplifying the message to their own followers.

While Facebook has a Share button on feed posts, its culture focuses on original content. Twitter happily embraces its re-sharing culture, which is very attractive to businesses because it gives them free earned reach. That means whether a merchant simply tweets a CardSpring offer or buys ads to show it to more users, if it delights people they’ll retweet it, netting the business new potential customers.