"Square" credit card allows private individuals to accept card payments

Click on this link to read a column that ran in the Sarasota Herald-Tribune business section (10-4-10) about a new credit card service called Square.  Whereas currently, only businesses can accept credit cards, Square allows private individuals to accept cards via a tiny free card reader connected to your phone.  Say, for example, a friend wants to borrow $20 from you.  You could slide his credit card thru the reader and be reimbursed by Square.  Do you think this next step towards replacing cash transactions with credit cards is a good idea?  See the article to read about the terms offered by the service.