[samatman]

I would say that for our purposes, the best example of jargon is the Jargon File: http://catb.org/jargon/html/

A useful quote from the above:

> Linguists usually refer to informal language as ‘slang’ and reserve the term ‘jargon’ for the technical vocabularies of various occupations. However, the ancestor of this collection was called the ‘Jargon File’, and hacker slang is traditionally ‘the jargon’. When talking about the jargon there is therefore no convenient way to distinguish it from what a linguist would call hackers' jargon — the formal vocabulary they learn from textbooks, technical papers, and manuals.

What you call new technical terms is the jargon of technical pursuits. The post modernism stuff is the jargon of "studies" departments. There is also military jargon, for another example. The term is not inherently derogatory.