Prof. Dave Farber sent an e-mail to his Interesting People list about how under Code Orange it is, apparently, illegal to take photos of transit facilities. http://www.interesting-people.org/ At a faculty meeting at Bryn Mawr College, the attendees were informed that a student from Haverford College was arrested for taking photographs of trains in Philadelphia. The student was detained and questioned for a few hours and eventually released. http://lists.elistx.com/archives/interesting-people/200302/msg00118.html
This struck a chord with me, as I like taking little travel pictures, many of which might take place in a bus, or at the station. I'm especially prone to take shots with my palmtop "spycam", though the pictures from that are weak, at best.
Fortunately, Farber also posted an item from a Portland, Ore. attorney who has posted a briefing paper about what your rights are as a photographer. http://www.krages.com/ThePhotographersRight.pdf