A friend of mine was over yesterday. He's a software engineer and works for the Bureau of Criminal Apprehension. He was telling me that part of his job is to maintain a system that scans license plates and runs checks on cars. The kind police use, that scan plates as they drive down the road. He says now if you pull into a Wal Mart or Target parking lot your plates will be read by sensors on the light poles, and a check is ran.
He was defending it as a great way to find stolen cars, but seems really intrusive and unnecessary to me.