Read about the Wolf Creek Lodge [via TreeHugger] in Grass Valley, California. The Wolf Creek Lodge is a "Cohousing" community for active adults. If you've never heard of cohousing, here's a description from the Wolf Creek website:
"Cohousing communities are small-scale neighborhoods that provide a balance between personal privacy and living amidst people who know and care about each other. Individual dwelling units enjoy convenient access to shared space including a common house with facilities such as a gourmet kitchen, dining room, laundry facilities, guest rooms, library and sitting areas, and workshops. Each home is entirely self-sufficient, complete with a kitchen, but residents often prepare common meals together in the kitchen of the common house."
The environmental benefits of cohousing are achieved through the sharing of resources and space.
While there are currently less than 100 cohousing communities in the United States, look for that number to grow as boomers look for ways to go green and also look for alternatives to the traditional retirement community concept.