Thanks for the very illuminating post on conspiracism. Two points I'd like to add.
1. The difference between power network research and conspiracism boils down to the treatment of counterevidence. A power network researcher may accapt the existence of a conspiracy if she finds evidence supporting it, but she has no problem rejecting a conspiracy hypothesis if there is no sufficient evidence to support it. A conspiracist, otoh, will not take "no" for an answer, he will believe in conspiracy regardless of emprical evidence. Insufficient evidence or no evidence to prove conspiracy? Evidence disproving that a conspiracy was involved? No problem - all that clearly "demonstrates" that conspirators meddled with the evidence, hence provides a further "proof" of a conspiracy.
2. I would not discount the psychological value of conspiracism. It is a form of symbolic control of an alien, incomprehensible,a nd hostile world. Ancient tribesmen depicted the world as moved by forces which their constructed in their own image - as humanlike forces. Hence, they appeased or fought those anthropomorphic forces to control the alien world through symbolic means. Anthropologits like malinowski demonstrate that such symbolic control persists only in the areas where people have no material means of controling their activity (e.g. open sea fishing vs. lagoon fishing which differed in the level of material control and the level of symbolic ritualism).
In the same vein, people who are both disenfranchised and lacking education accept conspiracism as a form of symbolic empowerment - by exposing the supposed conspiracy they symbolically thwart it, or at least are on the "top of it," as if "letting the cat out of the bag" stopped the ruling classes from implementing their "evil plans." It is, of course, a form of magical thinking akin to that of ancient tribesmen, but at the same time it gives a form of emotional empowerment to people who practice it. So criticizing conspiracism as superstition without giving the believers real means of influencing the polity might be robbing them of illusions that makes their life bearable.
wojtek