I am entering this discussion a month or two late, but felt I could actually add a resource. I live and work in Washington, DC, where you can just imagine all the issues with security and such, especially photographers. A dicussion went on about this in a local forum, if you are interested, found here: http://artdc.org/forum/index.php?topic=845.0
this instance involved taking of a social security number by the SS, Secret Service that is.
NPR did an episode on this very subject, here: http://www.npr.org/templates/story/s...toryId=4705698
And a resource form that discussion is a portable rights card, found online here: http://www.krages.com/ThePhotographersRight.pdf
Hope this helps a bit. I encourage all of us to continue taking photos even of the most suspect places or we will one day lose the rights to photograph certain public buildings or infrastructure, leading further down the path to a true police state.