For more, read this: http://facweb.cs.depaul.edu/sgrais/street_photography.htm
Photographing without permission
In the United States, anything visible ("in plain view") from a public area can be legally photographed. This includes buildings and facilities, people, signage, notices and images. It is not uncommon for security personnel to use intimidation or other tactics to attempt to stop the photographer from photographing their facilities (trying to prevent, e.g., industrial espionage); however, there is no legal precedent to prevent the photographer so long as the image being photographed is in plain view from a public area.
Publication
In general, one cannot publish someone's image to endorse a product or service without first acquiring a "model release," which is usually a contract between the publisher or photographer and the subject.
