Taking photos in NYC?

My husband and I are traveling up to NYC to see Ground Zero and a Yankees game and do a little sightseeing (Times Square, Broadway, etc). We have a Nikon d60 DSLR and were wondering if we are allowed to use it in NYC on the streets? It seems there is some kind of law going into effect in August (we are going in June) and we weren't sure whether our camera will be okay to use or not? Additionally, do you feel it is disrespectful to take pictures at WTC? My husband and I weren't sure. We just have the camera, not a tripod, and we are just amateur photographers.