Ref somewhere around here: http://www.story-games.com/forums/comments.php?DiscussionID=2977&page=3
I'm in a rush, though, so you might start some pages back. Though seriously, if you haven't already read that thread, this post probably isn't for you.
Okay, first of all, Fred gives exactly what I think are best practices.
Second, people keep talking about jargon being obscure and arcane; it's more than that, it's actually used (in the case of Forge jargon certainly) to paper over muddled thinking and/or to hide lack of intellectual consensus (and thus a basis for real communication) behind social consensus (which is just tribal solidarity).
Oh, third, discussion of games needs a critical vocabulary. Frankly this business about Forge jargon being the province of designers is a bunch of nonsense. It gets used as a critical vocabulary, not one I particularly like, but it's false to claim otherwise. So the retreat to "just for designers" really is elitist; if people really believed it, they wouldn't use it for critique. So the claim is just a way of cutting off meta-criticism of the ideology behind the jargon.