This week Yahoo! debuted its Yahoo! Green portal. The site’s key feature is a tool that asks visitors to pledge to take simple actions, such as buying 100% recycled paper or inflating their cars’ tires, and then calculates for them by how many tons of carbon dioxide they will reduce their carbon footprint. It’s an eye-opening tool, as the tons add up quickly.

But does Yahoo! walk the talk? It appears to be trying to do so. Yahoo! provides this information on its environmental services, most of which are pretty bland–a way to search for green goods or buy eco-friendly cars, for example–but way down at the bottom of the page we learn that Yahoo! is going carbon-neutral. And that’s a good thing, because Yahoo! apparently uses a lot of energy. On its carbon-neutral page, the company claims that “Yahoo! going carbon neutral in 2007 is like shutting off the electricity in all San Francisco homes for a month. Or, like pulling nearly 25,000 cars off the road for a year.”

Yahoo! also provides employee incentives for greener commuting:

Some of the services that we provide to our employees include shuttles equipped with Wi-Fi that connect with local transit stations in San Francisco and the East Bay, 25% transit subsidies, bicycle racks and lockers, showers, carpool matching, preferred parking for carpool and vanpools, 25% vanpool subsidies, and a monthly rewards program for employees who come to work without driving alone.