TechCrunch:

Square’s Keith Rabois also revealed a number of growth statistics for the company, including that the payments service is now processing $2 billion in payments volume per year. To date, Square has been activated by 800,000 merchants which is up from 500,000 card readers shipped in May. Rabois says that Square’s merchants are now 10% of the reach of the Visa/MasterCard world.

Square is the credit card processing service that works using a tiny card reader which plugs into your iPhone or iPad’s headphone jack. It’s a remarkable success story for the scrappy young company.

What’s unclear from Rabois’ comments is how much of that 10 percent of the reach is additive – in other words, vendors who wouldn’t otherwise process credit card payments because of the expense and hassle of “traditional” processing services. Square is quite popular with non-traditional merchants who, prior to Square, had cash-only businesses.