New Urbanism is a concept that I hear about a lot lately. In case you haven't heard about it yet, please refer to these definitions, sites and a video about the concept.
"Giving people many choices for living an urban lifestyle in sustainable, convenient and enjoyable places, while providing the solutions to peak oil, global warming, and climate change"
New Urbanism is "the most important collective architectural movement in the United States in the past fifty years." -New York Times
NewUrbanism.org was started in 1998, and has since grown to become a leading and well respected informational website promoting walkable urbanism, transit oriented development, trains and sustainability.
Here is a great short video on the concept of New Urbanism.
http://theoverheadwire.blogspot.com/2009/05/cul-de-sacs-kill.html
"Never doubt that a small group of thoughtful committed citizens can change the world - indeed it is the only thing that ever has" -Margaret Mead