Carbon footprint of Web servers and clients

An interesting article in the New York Times today talks about the energy and carbon footprint of the nation's six thousand data centers and quarter-billion PCs:

Up to two thirds of the electricity consumed by a PC is wasted, meaning the machine is on but not in use, according to the Department of Energy. The research firm Gartner estimates that 40 percent of the all carbon dioxide emissions resulting from information technology and telecommunications is attributable to PC’s. Data center servers, by contrast, represent 23 percent, though growing rapidly. (The rest is attributable to telecoms and printers.)

The solution? Simple software to put these units in "sleep mode" or power them down when not in use. In other words, turning out the light when the room is empty — for the Internet age.