Here in California (or Kal-lee-fohrn-yah, if you're the idiot we elected governor), we have a hands-free cell phone law. Simply put, if you are driving in California, you must use a hands-free headset or speakerphone device, no exceptions. We were mailed reminders from the state, AAA and even my school sent me a reminder, once the law was in effect.
But has anything changed? Not really. I do see more people walking around outside their cars with Bluetooth sets on. And the number of old folks I know (parents, aunts, uncles, etc.), complaining about how their wireless devices, "don't work," is on the rise. (They just don't know how to work them, truth be told.) But the number of people holding their cell phones, talking while driving? It seems about the same.
In fact, I notice it more now, I think.
Just goes to show you, you can legislate all you want... but the reality of life doesn't always go along with the laws you've written. I also find it odd that we were so quick to pass and implement this law, but it took our state months (past deadline, no less) to come up with an operating budget.