This article talks about green roofs and designing buildings from cradle to cradle instead of cradle to grave. I find these articles fascinating for the "open home" project I someday hope launch. In the end, if we want a long term sustainable life here on earth we need an open-home project and open-source government (with a different name, though). Home designs and materials list need to be shared. The future of life will be based upon the open-source concepts that have been widely used in the software industry for many years now.
These guys are suggesting that we use green roofs and also to take it a step further. To make them food farms! Imagine that! If every physical land footprint was a farm with a habitat underneath! Brilliant!
Read more here --> http://discovermagazine.com/2008/oct/28-king-of-green-architecture