Cohousing began in Denmark and was brought to the United States in the 1980s. There are over 200 cohousing communities in the U.S., including quite a few here in New England. Green Haven is the first in Connecticut though.
Cohousing is a form of intentional community in which shared values and a willingness to participate in the governance of the community define membership. But cohousing is also an architectural concept. Most American neighborhoods are designed around the needs of cars. Cohousing neighborhoods are designed for pedestrians, with cars relegated to the perimeter. This design principle fosters interaction between neighbors, which in turn helps build real community.
The Cohousing Association of the United States website is a great place to learn about cohousing. You may also enjoy this video.