This Economist blog post, written during the peak of the Wikileaks fightback - The 24-hour Athenian democracy - is pretty good, as the journalist actually gets to see how they were operating and seems to 'get it'.
Anonymous are a prototype human hive mind, the first of their kind (I
guess?). In that they actually aim to behave as a hive mind, rather than
a more traditional anarchist group or collective or suchlike. Which
makes them fascinating, but also very lowest common denominator.
(originally a comment from this metafilter thread)