I know that two of the big three auto makers have a policy that the security checks the cell phones of anyone who enters their plants. It seems that several months ago someone had a cell phone with a camera attachment and took a picture of a prototype vehicle 6 months or so before it was introduced. The picture ended up in an auto magazine.
If yor cell had the camera capability the security takes the phone, places it in a sealed bag and gives you a claim ticket for the phone. You pick it up when you leave the facility.