Twitter probably isn’t the first company that comes to mind when one thinks of mobile payments, but the company has just made a big play in the mobile commerce space. The microblogging site today announced the acquisition of payments infrastructure company CardSpring to help with "the future of commerce on Twitter." CardSpring gives developers the ability to add their own applications to the payment network so retailers can apply discounts and coupons at checkout and customers don’t have to deal with offline coupons. It also runs CardSpring Connect, a service that helps merchants manage the creation and deployment of special promotions for their businesses using services like FourSquare.