Consumption as political activism?

A popular statement about the new age is that we vote with our money. Since the new ruling powers are not the nation states, but the large corporations we as consumers are the new political grass root power which make impact by our daily purchases. Really? What political purchases have you done today?? In the article Let's Act Like Citizens, Not Consumers at http://www.commondreams.org/views03/0929-12.htm Betsy Barnum argue that consumer power is a myth and she has four pretty good reasons for saying so.