When hitting a milestone, some companies might send out a press release announcing the momentous news. But when your founder also founded Twitter, what better way to send out news than with a tweet? That's how Square let everyone know it had reached the $10 billion milestone.

Earlier today, Square, which was founded by Twitter co-founder Jack Dorsey, tweeted that it is now processing $10 billion in transactions on an annualized basis.

Square announced its milestone just a day after Bank of America said it would be entering the already crowded U.S. mPOS space, joining VeriFone, PayPal, ROAM and its white label partners, Groupon, etc.

What makes the milestone particularly momentous is that it doesn't even include transactions Square will be processing for Starbucks as a part of their agreement announced earlier this year. The $10 billion does not include that volume as Square is still in the process of taking on that task. However, Square is already processing all Square Wallet transactions at Starbucks. Square Wallet went live at Starbucks last week.

For more stories like this, visit the mobile/virtual wallet research center.