I have been looking around at some Green Roof examples on the internet and I have found a news article (albeit an old one) about Green Roofing of an entire community. This one happened in Toronto back in 1999.

The article described efforts of students, households, and other private and public groups to reclaim some greenery back into the concrete jungle. Quite an effort really, considering there was massive education and information dissemination required.

I also found a blog that talks about green roofs from an architectural perspective. You may want to check that out too here.