Privacy in the Woods?

Rorschach1 asks: "I work with a local Search and Rescue team, and for some time I've been thinking about the possibility of installing sensors at a few critical trail junctions in the local back country. The sensors would detect passing hikers and report timestamps to an Internet gateway in near real-time. When a hiker goes missing, this information could be very valuable in determining where search efforts should be directed. However, I've spent enough time on Slashdot to know that whenever you start monitoring or tracking people and their activities, someone's going to get upset. So I'd like to hear from the tinfoil hat brigade - what are your objections to such a system, and how might your concerns be addressed?"