Read my analysis of research into cell phones and driving
. I believe that the studies done to date all suffer from some problems in scientific method. Most of them fail to take into account what I call the 'human factor'. Most people are not idiots, they will not continue talking on the phone (or doing any of a number of other distracting actvities; eating, hunting for a CD, changing the radio station, dealing with a fussy child, etc.) when they are in a dangerous driving situation.
Here's the simple synopsis, if cell phones are truly a big distraction, explain this chart:
Accident rates continue to drop despite exponential growth in cell phone usage. Either people are not talking on their phone while driving, or using a phone while driving is not dangerous. Either way, I don't think we need legislation preventing us from doing something that is clearly not a significant danger.