While i'll admit that I haven't read all of the postings concering the placing of caches in caves....I will put in my 2 cents worth here.
I am the leader of a BSA Troop here in Oklahoma City.
We've gone splunking before w/trained professionals who were able to show us safely through a wonderful wild cave in the NW part of our state. It was a great time - but the basic rules were in effect then as they are at all times. Take only pictures, leave only footprints.
You don't pick up rocks, shells, artifcacts, etc...that you might come across while in a cave (for example) simply because if everyone did this, damage beyond repair would happen.
Now - dealing w/placing caches in caves....Personally, I think it's a poor idea. Why? because I think the use of a wild cave (a cave that doesn't have guided tours, etc...) could be tremendously dangerous to the average person who really doesn't know how to deal with exploring a cave - they have just one thing on their minds - that is finding the cache - in fact, I would doubt that much time at all is spent noticing the beauty of the cave. I could be wrong of course, but I am probably not far off when I say that a good number of folks that would go looking in a cave don't have the proper gear to do that - don't have the respect (because they are not properly educated in caving perhaps??) for the cave that they should have, and simply don't see the problem with moving rocks - digging perhaps, hammering, etc...
My opinion then would be - take only pictures, leave only footprints, and leave exploring caves to those who are trained to do so, and could take you safely into that environment.
Caves are a fascinating "world" - I love to explore them - but I would still vote to not allow caches into caves...
...Scoutmaster23