David Neiwert has some great material on fascism: what it is, what it isn't, and how people and societies get there. Short answer: what it is is amorphous, nativist, and reactive; what it isn't is conservatism per se, solely Nazism, or characterized by goosestepping brownshirts. As for how socities get there, Neiwert has a chilling quotation from Milton Meyer's They Thought They Were Free:

What happened here was the gradual habituation of the people, little by little, to being governed by surprise; to receiving decisions deliberated in secret; to believing that the situation was so complicated that the government had to act on information which the people could not understand, or so dangerous that, even if he people could understand it, it could not be released because of national security. And their sense of identification with Hitler, their trust in him, made it easier to widen this gap and reassured those who would otherwise have worried about it.

Very disturbing, especially in light of the simple truth that fascism is not either Nazism or simple-and-easily-understood evil. It is a political position, one that was very popular in the early part of the last century and which can be as virulent as any other political meme. More so, actually, because fear is the meat and drink of fascism, and there's rather a lot of fear going around nowadays.