Congrats on their launch, but I honestly can't see too much of a market for their product. I would expect most businesses to get a proper merchant account and maybe a mobile payment device from Verifone or Visa.

Square can't compete directly with those companies which have established brands and a long history in the payment industry. They might be able to target the folks who only occasionally need to process credit cards - say at a farmer's market, food cart, or when selling something on Craiglist.

But are there really enough people doing that are:

  - Too small to get a full merchant account
  - Not willing or able to use PayPal
  - And wanting to take credit cards instead of cash/checks and eat the fees?