I randomly came across this article in Science, from 2009.  If you aren’t at a campus library, or otherwise privy to an academic-journals subscription, the full text will be tied up behind the paywall.  But Jayne Wilkins, a Toronto Ph.D. student who writes at Suite101, offers a nice synopsis.  Meanwhile, closer to our own setting, New York magazine has dedicated much of its current issue to global trends in urban planning, with a focus on the design of cities.