For anyone serious about reducing their carbon footprint of their marketing efforts, the hosting of your Web site in a green data center is a great idea.

Here is an article on green data centers, which is a step beyond some other the other options, such as using a hosting plan that buys green energy credits:

http://www.pitchengine.com/green-data-center-titles-released-from-pearson/22803/

From a marketing standpoint, it's a great idea to pay the little extra for a green hosting plan especially if your company is large enough that the energy to run your IT systems burns a lot of fossil fuels. Today's green watchdogs are looking for transparency and this is another way to be transparent.