I forgot to mention a few more things about the DMZ. We also took a tour of the 3rd Tunnel of Agression the North Koreans were digging to get to Seoul. Sadly, no one can take photos, but you can see some photos of the maps on the wikipedia page.
The Wikipedia page on the DMZ is interesting. There you will find a picture in the Joint Security Area almost exactly like the one I took of the guard and a guy in the window with binoculars. In their photo the guard has binoculars too. They also talk about the fake North Korean town of Kijong-dong. The town is like a set for a movie, with no one actually living there.
North Korea is absolutely fascinating. If you get a chance, I suggest reading
It was highly entertaining and informative, although I took it with a grain of salt.