Sorry to hear about that......I had the same thing happen to me this year, but had a better than expected outcome.
I had placed a camera on a remote spring in some blacktail country here in Kali. When I returned two weeks later, I noticed someone had taken my card out of the camera and turned the camera off. I was pretty upset, but glad they didn't steal it. So, I put in another card, turned it on, and left. 5 days later I checked it again and opened it up. There was a note inside along with my original card AND a brand new 2gb card. The note basically said they didn't want to place another camera on the water and infringe, but wanted to see what came in. So they viewed my card and returned it two days later. The note also added that since they viewed the card, they turned it off to save battery life and gave his name and phone number to see if I was going to hunt it. I was actually pleasantly surprised by the note and ended up calling the guy after I viewed the deer on the card. Nothing real big but big enough for this guy. I told him to go ahead and hunt it and thanked him for the card.
I guess I could have been upset that he viewed my card in the first place.......but out here (CA), I was simply glad my camera was still there and not vandalized. Besides, I basically ended up with an extra card just for letting him view it.