I'm still a Gilette Fusion man myself but I might finally switch to an electric shaver after reading the carbon footprint breakdown: Electric razors use 30x less energy.
How does Slate figure? An electric razor runs on 5-6 watts, consuming 0.35 kilowatt-hours a year. But! Most dudes using a disposable razor use a quart of hot water, using 10.4 kilowatt-hours a year.
All told, when you consider other elements, like the CO2 produced by making each disposable razor and the like, an electric razor will save you 14.9 pounds of carbon dioxide per year—which isn't a lot—but every little bit helps. I suppose if you wanted to go ultra green, you could go ultra badass: a straight razor with no water.