Interesting points....here's what happened to me.
My company has been contracted to do a "Homeland Security" site survey of all the water tower tanks in the county. We are using wireless to tie all of the sensors together to form a "security web", and I had to add a stumbling setup in my company truck to do the wireless survey (Okay, so they had to "twist" my arm! ; ) ). The setup consists of a roof-mounted 7 dBi omni, a Sony "picturebook" (please, no laughing...it works and is small) mounted on a vehicle laptop mount, Orinco card, GPS, etc. Add all of that to the other antennas I have mounted and...well you get the idea. Looks like something out of the next Austin Powers movie!
I was stopped at a license checkpoint, and the State Trooper asked me to pull off the road. He looked at the setup, walked back to his car and talked with his dispatcher (which I overheard, as we also maintain several of the law enforcement communications systems). Seems he thought he had collared a "would-be terroist". He came back to me, hand on his weapon and asked me to please step out of the vehicle. Of course I did, VERY slowly. After the usual inspections (license, registration, insurance), he began to ask what was I doing. I simply said that I had been contracted to do some work under the "Homeland Security Act" (true), that the work I was doing was classified (again, true), gave him the number of the county manager's office, and any further questions would have to be answered in the presence of his Captain. He went back to his patrol car, talked for a while on his radio (which I didn't overhear, as I was outside my truck), handed me back my license, et all, and said, "Sorry for the misunderstanding, sir. No further questions will be necessary." For a moment, I thought he was going to salute!
My point here is that even though what we do is for "fun", 9-11 has changed many facets of that definition. Fortunately, I was in a position that helped me avoid a trip to the "pokey" for further questioning. Being truthful, respectful, and professional in dealing with LEO's goes a long way, both for us AND them. My thinking is that if "we" can find it, sniff it, crack it, then so can "they". Didn't mean to climb up on a soap-box, but these are strange times we live in. Keep stumbling, but let's be careful out there! What we crack today, may save us tomorrow!