From the San Francisco Chronicle:

Greenpeace International ranked Apple Inc. last in environmental friendliness among major electronics makers, while it praised Lenovo Group Ltd. for bucking trends in China.Greenpeace spokeswoman Iza Kruszewska said Apple has been willing to meet legal requirements and basic standards, but it hasn't stopped using several types of harmful chemicals in its manufacturing.

Greenpeace Ranks Apple Last for Green

When "Refurbished" Takes on an Earth-Friendly Vibe - New York Times

I have always found that refurbished computers are nothing short of a fantastic deal- both for your wallet and for your social conscience.  As this New York Times article points out, often times refurbished computers haven't ever been really used.  Every refurbished computer that gets purchased is one less computer in the landfill.  Consider it for your next computer.