How, then, did OWS embody anarchist principles? It might be helpful to go over this point by point:
The refusal to recognise the legitimacy of existing political institutions.
One reason for the much-discussed refusal to issue demands is because issuing demands means recognising the legitimacy - or at least, the power - of those of whom the demands are made. Anarchists often note that this is the difference between protest and direct action: Protest, however militant, is an appeal to the authorities to behave differently; direct action, whether it's a matter of a community building a well or making salt in defiance of the law (Gandhi's example again), trying to shut down a meeting or occupy a factory, is a matter of acting as if the existing structure of power does not even exist. Direct action is, ultimately, the defiant insistence on acting as if one is already free.
The refusal to accept the legitimacy of the existing legal order.
The second principle, obviously, follows from the first. From the very beginning, when we first started holding planning meetings in Tompkins Square Park in New York, organisers knowingly ignored local ordinances that insisted that any gathering of more than 12 people in a public park is illegal without police permission - simply on the grounds that such laws should not exist. On the same grounds, of course, we chose to occupy a park, inspired by examples from the Middle East and southern Europe, on the grounds that, as the public, we should not need permission to occupy public space. This might have been a very minor form of civil disobedience but it was crucial that we began with a commitment to answer only to a moral order, not a legal one.
The refusal to create an internal hierarchy, but instead to create a form of consensus-based direct democracy.
From the very beginning, too, organisers made the audacious decision to operate not only by direct democracy, without leaders, but by consensus. The first decision ensured that there would be no formal leadership structure that could be co-opted or coerced; the second, that no majority could bend a minority to its will, but that all crucial decisions had to be made by general consent. American anarchists have long considered consensus process (a tradition that has emerged from a confluence of feminism, anarchism and spiritual traditions like the Quakers) crucial for the reason that it is the only form of decision-making that could operate without coercive enforcement - since if a majority does not have the means to compel a minority to obey its dictates, all decisions will, of necessity, have to be made by general consent.
The embrace of prefigurative politics.
As a result, Zuccotti Park, and all subsequent encampments, became spaces of experiment with creating the institutions of a new society - not only democratic General Assemblies but kitchens, libraries, clinics, media centres and a host of other institutions, all operating on anarchist principles of mutual aid and self-organisation - a genuine attempt to create the institutions of a new society in the shell of the old.
Why did it work? Why did it catch on? One reason is, clearly, because most Americans are far more willing to embrace radical ideas than anyone in the established media is willing to admit. The basic message - that the American political order is absolutely and irredeemably corrupt, that both parties have been bought and sold by the wealthiest 1 per cent of the population, and that if we are to live in any sort of genuinely democratic society, we're going to have to start from scratch - clearly struck a profound chord in the American psyche.