I saw a news report of a small device that warns people of traffic cameras so I googled and this is some info I pulled up on the internet about it so far
Here is one of the devices they were talking about Clicky
I wanted to post a pic of device cause most people probably think its talking about the Navigation unit in the dash but here is what they are talking about in video !
I know iphone has similiar App you can use it works best on 3G network with GPS Here is the app Clicky
NOTE : 99% of traffic cam tickets can be won in the US court system, most of them do break constitutional laws but usually without an attorney you will probably just pay the ticket ! I know people who had attorney's that did get Photo radar tickets and have won just by having an attorney.