Popular Science just published an interesting roundup of green communities in an article now titled, “Nine of the World’s Most Promising Carbon-Neutral Communities.” You’ll recognize several of these communities as we’ve mentioned them previously. What’s important is the notion that reducing an environmental impact can be ultra effective when done on a large scale. Here’s the list: Best U.S. Project: Greensburg Holiest: Vatican City Fastest Transformation: Samsø Island Most Urgent: Maldives Most Expensive: Masdar Most Ambitious: Costa Rica Smallest: BedZED…