I was just reading Larry Borsato's blog (from seeing the Communitech Chapter 3 blog ...) and I saw his post about jargon . Jargon actually does have a useful function as culture. For example, recently I've been writing a business plan for my company and I've had to learn some new words, like valuation. Valuation is a bit of a jargon word since it really means the appraised price. The person on the street knows what "appraised price" means but not "valuation" ... but that's actually valuable because it's a cultural clue. If I go up to someone and start talking about valuations it tells them that I know about business culture, VC culture, and whatever.
The same thing goes for social culture... if I start talking about chavs to someone, they would probably assume I'm british (I'm not but I think it's a funny word).
There's also another strictly practical use. If I type "valuation" or some other jargon-term into google, I will restrict the field of the search to the cultural context I'm interested in, in this case, business planning, VCs, M&A, etc. If I put in "appraised price" or even "value" I would get something different.