Although I believe the ranger overstepped his bounds and acted with undue suspicion under the circumstances, my colleague and I reacted–in my opinion–in a completely appropriate way. We were very polite and understanding of the issues at hand and we recognized that Tennessee might do things a little bit differently than Connecticut. For example, in Tennessee, photographers get frisked under suspicion of poaching.
Anyway, it's a good idea to hold up your end of the bargain if you do get approached by an officer of the law, and to act in a way that reflects positively on yourself and on all of us as photographers. Especially if there is a video camera in the officer's car…
Yesterday, I ran across this article, 5 Things Photographers Should Do When Confronted By Police It contains some helpful tips and might be useful to you in your travels.
It's also a good idea to know your rights in these situations, and to help you I will once again point you toward Andrew Kantor's Legal Rights of Photographers (pdf) ((Linked with permission. If that copy is down, get it from me )) guide, a somewhat abridged yet very straightforward and understandable overview of your rights as a photographer (at least in the United States).
For a slightly more technical view, you may wish to read The Photographer's Right.htm by Bert P. Krages II (attorney at law). Although no advice given by an attorney from outside of your state could be said to be formal, anyone out there from Oregon just struck gold. For those of us who aren't from the pacific wonderland, at least you can say that this advice was cobbled together by someone with actual legal training.
-If you want to dive in yet further, please do visit the forums at PhotoPermit.org where you can read all about your rights, current events, and first-hand accounts of being hassled or confronted by authority figures both various and sundry.- [Edit: Apparently photopermit.org has now been replaced by a spam site. Condolences.]