Square Provides Easy Alternative to Cash and Checks, TidBITS article.
Square opens up to individuals the option of accepting the third major payment method we use today — credit/debit cards. The payment side is far from new — we’ve all been paying for things with credit cards for decades — but until Square, receiving money via credit or debit cards was far beyond many small companies, much less individuals, due to the effort of setting up the necessary “merchant account” and dealing with the fuss of processing cards.
A very nice improvement in personal/small commerce and money exchange.
It doesn't seem to be for web merchants though, only for when you have the customer and his card in front of you, or at least on the phone. I asked Engst about it:
It's not clear to me if you can use square over the Internet. Take payments from your web site for example?
Technically speaking, yes, but people would have to send you their credit card numbers for you to enter by hand. It's really made for in-person transactions.