In the April, 2006, Reason (no link available yet), Bob Nelson writes, "Local government has been increasingly privatized since the 1960s. I don't mean government services; I mean government itself. In 1965 less than 1 percent of all Americans lived in a private community association. By 2005, 18 percent -- about 55 million people -- lived within a homeowners association, a condominium, or a cooperative. Since 1980 about a half of all new housing units in the U.S. have been built within such associations; in California, the figure now is at least 60 percent."
Impressive numbers. But the phenomenon, as far as I can tell, is largely ignored in the academic urban planning journals. When it is cited, it is wrongly characterized as all about gated communities, which constitute a very small part of the trend.
Bob Nelson has been documenting the rise of private communities for many years. He elaborates in his 2005 book, Private Neighborhoods and the Transformation of Local Government. I have been using it in my economics for real estate developers class.
Chris Webster and Lawrence Lai, in Property Rights, Planning and Markets (2003) elaborate five emerging spontaneous orders:
"Organizational order emerges as individuals pool property rights to form firms. Institutional order emerges as society invents systems of rules and sanctions that reduce the costs of competition. Proprietary (ownership) order emerges as those institutions allocate property rights over scarce resources. Spatial order emerges as individuals and firms seek locations that minimize both travel-related transaction costs and information search costs and that balance these against congestion costs of crowded cities. Public domain order emerges as individuals engage in collective action through governments and other agencies to clarify property rights over jointly consumed goods (externalities, public goods and natural resources) and thereby to reduce the costs of competition and in the extreme, the costs of anarchy."
Several of these orders are evolving simultaneously in the private comunities trend that Nelson writes about.
And events are undermining planning dogma which remains stuck in the time warp of top-down ("sustainability") planning.