Joi Ito blogged about the announcement by Sony and Docomo that they are teaming up to put contactless chips in telephones. I recalled how easy it was, my last couple trips to Tokyo, to buy a Suica card at the JR station, then just wave my wallet over the turnstile when entering and leaving stations. Waving your telephone over a vending machine or a payment point at a grocery check-out makes sense. But as Joi points out, it will take some bold moves on the part of private industry and government for this kind of digital cash to achieve critical mass.