This is one of those links I knew would be useful someday…
Tribalized Communities and the Megapolis, Detailing the dynamic relationship between the two, of note for the recent-most discussion.
It is one chapter of an online text entitled Forming Tribalized Communities. This will be of interest to those interested in political and social aspects of building sustainable culture.
More generally, the parent site WeChange offers articles and forums on sustainability. There seems to be a lot of information there, it may be worth exploring further, wading through rhetoric as required.
-steven