Wow, most stores around here deal with this by banning photography inside their stores and confiscate cameras and delete the photos if your caught taking pictures of their prices. They then ban you from shopping there.
"A social worker from New York City was arrested last week while in Pittsburgh for the G-20 protests, then subjected to an FBI raid this week at home -- all for using Twitter. Elliot Madison faces charges of hindering apprehension or prosecution, criminal use of a communication facility and possession of instruments of crime. He was posting to a Twitter feed (or tweeting, as it is called) publicly available information about police activities around the G-20 protests, including information about where police had issued orders to disperse. "