The Olympics can never be green, given that countries spend $14 billion tearing down and building stuff and then people fly and drive in from all over the place to watch.  But they can at least be relatively green.

 As Melissa C. Lott at Scientific American Blogs notes, the Brits did it right; the event was built with sustainability as part of the planning.  From recycling to energy efficiency, plenty of their materials and buildings are being repurposed, so in the Green Olympics of Olympics, London is #1

Sustainability Gold for the 2012 London Olympics By Melissa C. Lott, Scientific American Blogs