I think that the forms of community that stand the best chance are traditional "unintentional communities"...tribes, villages, and extended families; who live and work together because they have to and have known no other way, least of all the addictive influences of modern culture. "Intentional communities" within the matrix of mainstream culture are all to some extent swimming upstream and trying to learn forms of social "remedial common sense" Some of the most successful include groups with a strong shared spiritual belief and practice (the Amish, the Bruderhof) and/or a strong leadership (though these often break up when the founder dies). I'm simply saying these groups are successful in maintaining their community life over the long haul. I too value choice and freedom of expression enough to consider living in such groups to be oppressive. I've sometimes concluded that the main purpose of money and private property is to keep us out of one another's hair! Many groups and movements that come together suffer from the "too many chiefs and too few braves" syndrome.
The notion of private property is one of the major issues behind mainstream culture and one that is blurred or transcended by its predecessors and its modern alternatives. Many small communities founder early on because they are started by one or a few founders with the resources to obtain land, and people who join later never get to become full part-owners...the founders end up functioning like an oligarchy. Any permaculture site with an owner or two and a group of interns and WWOOF'ers can feel and function like a community... the problems start when one of the newcomers likes it so much he/she wants to stay on.
Traditional villages, of course, have their power dynamics and family feuds and so on, but there's often the sense that "we have to make it work"....in ancient times, banishment usually meant death.
Enlightening information germane to this discussion can be gleaned from the study of the interaction between the Western cultures and aboriginal peoples around the world. Invariably, the notion of private property (especially in regard to land) was simply incomprehensible to the natives, and this incomprehension aided their expropriation and exile. Another tidbit, at least from the American frontier, was the native incomprehension of the Western work ethic...time and again one reads accounts of native peoples gathering simply "to watch the white men work"...busy at what was then called "improvement" (clearing, burning, plowing, building, etc.) They simply couldn't grasp what would possess people to work that hard, that long, to obtain food and shelter that, to the natives, could be obtained with a lot less effort. Of course part of it was the white culture was attempting to support a denser population, and often an export economy as well.
This is interestingly one of the biggest "lifestyle" notions I am struggling with while learning about permaculture.
It's obvious the very foundations of it are centered around the developing of healthy communities where skills and harvests can be shared, in fact I don't think one could really get the full benefit of the idea of permaculture without a connection to at least a single community.
Yet I find myself utterly switched off to community. I feel as if without some sense of an "equal trade" that it would be akin to giving away hard work. It's different if you willingly work for somebody else, but is there not some reward in that itself?
Brought up on capitalism? Probably. Fearful of corrupt communities? Maybe.
I like adiantum's suggestion of unintentional communities though. I've always thought necessity was always a strong motivator.