SquareOne of Twitter’s co-founders, Jack Dorsey, is on the cusp of changing how we all do business with his latest contribution to the world of mobile commerce: Square.

This tiny device is something previously unknown.  Now, anyone, anywhere, anytime, can accept a credit card payment for anything.  Plugging into any phone with an audio jack, Square will allow you to accept payment, provide receipts, offer rewards to your consumers and donate to charity without a contract.  Square promises to change the way we all do business and if even half of what it promises to deliver proves to be true, it most certainly will.

UPDATE: According to this article in the LA Times, Jack Dorsey now says that it’s likely that when the Square is properly introduced, it will be offered for free!  Woo-hoo!  Thanks to our own Kyle Allkins for the link, which apparently he found by Twitter-stalking Alyssa Milano.