DykstraDynamo: Well, after a thorough search through the thick brush and masses of poison ivy, we've determined that the cache is gone. If I was a spiteful person, I might wish the thief got a good dose of the ivy. Time will tell if I am indeed immune to the stuff - to date, I've never had it affect me, and I'm not very good at identifying the stuff (which is how the cache ended up in a patch of it in the first place!)
We'll place a new cache in a new location (without the ivy) soon!