I know some churches that have looked into cell phone signal blockers. Apparently they're illegal in the hands of private citizens.
There may be technology solutions. It isn't hard for the industry to create something that blocks certain cell phone functions when a car is in motion - that's there in some apps, and in Garmin GPSs, but it's voluntary; this would have to be mandatory to be effective. But can technology block the driver without blocking the passengers? There may be a way to do so, but I can't visualize it. Ultimately, the answer still comes back to people behaving responsibly and accountably when behind the wheel of a car - or for that matter, in the seat of a motorcycle.