Google's Energy-Saving Replacement... Blackle?

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I don't know if much of you have heard but Google.com has made hundreds of sites stemming off Google. Another new site has appeared. Blackle (blackle.com). The main premise of the site is to save energy. How? Getting thousands of people using it eventually adds up to thousands of saved Watts (less light-energy consumption). What are your opinions about blackle.com ?