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.

Olympus
Single & Not Looking
They just installed some traffic cameras out here, and for about 30 days after they installed them, they gave the people around here a grace period, so if you got caught in a "flash", you didn't get a ticket or anything. I'll admit, I got nailed once.
I'm not against the idea, but at the same time, I think at least as far as the locals, they'll just remember which lights have the cameras, and be cool around those lights, and drive as usual everywhere else. But, this is also a tourist trap so alot of people won't know about them. Another way to bring in some money I spose ...