Kibosh, if this were a cross-genre group to begin with, that would be a great idea. But as Blue mentioned, it's really a matter of comfort with the people you're trading with. We'd all like to think the best of people, but unfortunately, for every generous person out there (and there are many!) there are easily just as many willing to rip off the whole lot. It's easier to keep track and avoid those people within the smaller communities that we have set up. For instance, while I don't post often (and so some people might not know me), I've traded with a fair number of people on these boards so that my reputation could be vouched for if my actions were ever called into question. If I just showed up from Classic-Space.com... no one here would likely know me and even if I had someone who vouched for me from there... that person might not be known either.
Ultimately, the whole idea of Jambalaya is to have fun, perhaps get a few pieces you didn't have, and pass on some pieces you might not have needed.
I'm going to put a box of parts/pieces together this weekend. It'll probably be a mixture of bricks, minifigs, and minifig items. I'm not sure of the size/value initially, but if anyone has any "requests" for starter composition (not that they'll still be there when it gets to you

) please feel free to chime in here or PM me. Once I have the box ready, I'll start a new post with the rules for entry and then line up the addresses lists.
For those of you who do play cross-genre, I started a similar interest thread on ForbiddenCove.com (the Pirate Lego enthusiast forums similar to CC). You can find that thread
here.