Serial entrepreneur Jack Dorsey must have the magic touch. After leaving Twitter for another venture, the microblogging service's co-founder hit the jackpot anew, this time with mobile payment processor Square.

You may be familiar with Square as the plug-in device that connects to any compatible smartphone or tablet — including the iPhone, iPad and Android devices — enabling the device to accept credit card payments. It seems there's no stopping Square's success, as the company reports processing payments at the rate of US$ 10 billion per year.

Just two months ago, the company's estimates were at US$ 5 billion annual transactions. With this growth, Square is poised to dominate, which might become a problem for other payment gateways and systems like ISIS and perhaps even Google Wallet and Apple's Passbook.

What makes Square click? Perhaps its partnerships with establishments, like Starbucks, helps get visibility for the platform. It helps that users still prefer swiping plastic credit cards today rather than use an alternative system, such as NFC or app-based payment.

It also helps that Square is trying to enter into markets outside of the U.S., with its recent launch in Canada and soon in other regions. What's even more interesting, though, is that the $10 billion figure excludes transactions made within Starbucks, as reports TechCrunch.

Of course, given the innovative payment methods and features that its competitors are offering — like loyalty rewards, transit tickets, and the like — Square will either need to improve its product offering or keep focusing on what it does best.