http://lens.blogs.nytimes.com/2010/10/18/you-can-photograph-that-federal-building/?hp

The right of photographers to stand in a public place and take pictures of federal buildings has been upheld by a legal settlement reached in New York.

In the ever-escalating skirmishes between photographers and security agencies, the most significant battlefield is probably the public way — streets, sidewalks, parks and plazas — which has customarily been regarded as a vantage from which photography cannot and should not be barred.

Yes here here for the rights of photographers Bruce. I know that I'm NOT going to bomb what I shoot, so I continue on no matter what!

My wife and I stopped in the large parking lot of a local federal building at night to try a few shots of a lunar eclipse.  It took only a moment for a security vehicle to come beside us and ask what was going on.   In this case, the guard stepped out and took in a view of the moon.  The guard kept some distance from us and the vehicle between  but there was not a mention of the camera.  I am sure other guards might be more invasive...and some may not know the new regulations.  Of course, we were in their parking lot and could have been asked to leave perhaps.

Thanks for the heads up.

About two years ago I took my two teenage children to Washington, DC.  We were in the car on the street beyond the parking area that surrounds the Pentagon.  Both my children snapped a picture from the moving car.  Within seconds, literally, we were stopped by security officers and my children's cameras siezed  and the photos deleted.  Scared my kids to death. 

all this security threat has made life a lot harder than actually feeling safe when going out. incidents like these have happened with me as well and now every time i shoot a public office, i just wait for them to arrive.