Thousands of people have seen it on the road and they are in a much better position to yews that information than someone half way across the country or world. It's not any different from driving down the road or leaving your car parked at the grocery store.
It's literally no more dangerous than having my name displayed on Facebook. Someone could easily take my name to ancestry.com and theoretically learn my address that way.
You can find out much more from the IP address you're posting from than your license plate, or from photos that you've posted that are potential geotagged (many are nowadays.)
I once tracked down a friend of a friend's location from a skype group call by running all the IP addresses that were connected to my PC during the conversation. It took probably 15 minutes of trial and error, but eventually I guessed correctly (it was somewhere in Florida, I think.)
Anyone who wants to prove me wrong, have at it. Feel free to PM me my address or something when you get it. No using squad cars.
Edit:
http://en.wikipedia.org/wiki/Driver%27s ... ection_Act(If you want to hire a licensed private investigator just to prove a point, be my guest.)