This is older news but important—apparently the U.S. entering the 21st Century! Whereas everyone and their Mom already has cellphone-enabled payments, this new Paypal system will allow you to send and receive money via SMS.
Like the inimitable CueCat and other devices that came before it, the system will also allow you to purchase items you see in magazines and posters by sending money to a certain number. Will it work? It has definite potential, and the PayPal name has quite a bit of cachet. Why didn't the carriers do this, though? Oh, I forgot. They're all dumb and scared.