According to this article, postmodernism seems to be, in its barest essence, a form of impious iconoclasm as applied to the analysis of traditional concepts. It's a very honoured tradition in Western Philosophy: in one century of democracy, the Athenians managed to practically destroy their entire body of traditions by discovering the base, petty group interests behind the so-called "sacred" and "natural" laws of their City.
Let me just say that I don't think that post-modernism can be thought of as Socratic iconoclasm. I think it has valuable insights, many of which have been co-opted by more "rationalist" philosophy.
For example, I don't think Michel Foucault can profitably be described as a nihilist. And whatever his sympathies to the Soviet Union (it appears that it was different at different stages of his life), I think the idea that he was generating poison-memes on behalf of the Soviet Union is ludicrous.
I have found this most wonderful (if fairly lengthy) article, and thought you would enjoy having it brought to your attention.
It is so good, I think we should include it among the references in the "Politics is the Mind Killer" wiki page. But, before that, I submit it to you, and ask you: is there anything in this article that would warrant its exclusion from this site? I mean, besides the fact that it is about politics, and written by a notorious Social-democrat (And is that in itself grounds for exclusion?).