I guess if you feel uncomfortable with it, don't bring your gear at all, (which would be unfortunate, and kind of defeats the purpose of the meet altogether), or if you have some particular item(s) that you're concerned with, lock it in the car when it's not being used.
I'm going to have tags on all my gear, so hopefully if someone is putting stuff in a box to go home, they'll see the tag and say, "Oh, this is tenzip's, I grabbed it by accident."
I know there are "lost and found" threads after big meets, for things that got into the wrong box, but I don't think it will be a problem. Having a list and checking it twice seems like a good idea. I know I plan on bringing some extra stuff like power strips, RCA cables, etc., for the inevitable "Darn it, I left that sitting on the table at home".
If everyone hasn't read the sticky threads at the top of this sub-forum, please do. One of the things mentioned is, if you want to take headphones or something else from someone's rig to try it with another, or make changes in the setup, get permission first.
As far as criminal intent, I guess I have to say I hope nobody is making that part of their meet plans.
I spent quite a bit of time editing and re-editing this post, and I probably could have edited everything out except the first paragraph.