Starting in 2008, every new yellow taxi purchased by the city of New York will be a hybrid vehicle, according to an announcement yesterday by Mayor Bloomberg. By 2012, the entire fleet -- some 13,000 cabs -- will have been replaced with a mixture of Toyota Priuses, Highlander Hybrids, Lexus RX 400h's, and Ford Escapes.

Thirteen thousand may sound like a drop in the ocean, given that 232 million cars are currently registered in the U.S. alone. Still, cabs are a great target for greening, both because of their high public profile and because of their disproportionately large carbon expenditure. New York City never sleeps, and neither do its taxis, ever spewing their emissions, even while they mostly idle in traffic.

Bloomberg certainly is the consummate businessman, as you can see in this Today Show clip -- adept at rubbing shoulders with corporate execs from Yahoo!(which donated 10 hybrid vehicles to one of the major cab fleet operators) to the American Lung Association. One gets rolling advertisements, the other gets less asthma ... and we all get slightly cleaner Big Apple air.