Best Buy, Target, Walmart, The Shack, Apple. All of the above are now proudly selling the Square credit card reader, according to a tweet sent out by CEO Jack Dorsey. It's great news for anyone willing to shell out a ten-spot in order to conduct business from their iOS device right away, rather than waiting between two and five days for a free one to show up in the mail. If you need one today, you'd best be calling up your local retail outlet to make sure they have some in stock.