I've seen the drunk-driving = cellphone-while-driving study.
Judging from what I've seen, I believe it.
The editor of Road&Track magazine just did a piece on this subject.
I have followed literally dozens of cars wandering back and forth between lanes and going 10 mph under the limit.
These days my normal reaction to such driving is: "That person is either drunk or on a cell phone".
I've seen two accidents in the last year by cell-phone "talkers". One involved a guy who rear-ended someone and another where a woman ran right over a large dog while on the phone (she could have easily missed it...she never even applied the brakes until afterwards).
And I do not personally believe that the hands-free units help very much....the person is still distracted.
And I have seen folks text-message and using Blackberries while driving. How can anyone be so indifferent about the safety of themselves and others? Beyond belief to me.
Also, I am amazed how folks "assume" it's OK to use a cell phone while in a public place such as a grocery-store line, book store, subway, etc. The people around them are essentially "trapped" and forced to listen to their yammering. On the rare occasions when I use a mobile phone, I pull over or if I am on foot, I move away from other other people.
Sadly, it seems safety and common courtesy are "out-of-fashion".