Q:

What states have regulated the use of mobile phones while driving?
A:

Twelve states in the South have some regulation of mobile telephone use while driving.

The table below outlines the relevant legislation:

Arkansas
 HB 1042 (2003): prohibits the use of a mobile telephone while operating a school bus.
Florida
 SB 358 (2002): requires the Department of Highway Safety and Motor Vehicles collect statistical data for annual reporting of “driver distractions.” 
Kentucky
 HB 154 (2003): prohibits local governments from passing restrictions on mobile telephone use while driving.
Louisiana
 HB 1207 (2003): prohibits local governments from passing restrictions on mobile telephone use while driving.

HCR 35 (2001): creates a task force to study the dangers of distractions while driving.
Maryland
 HB 394 (2005): prohibits the use of a mobile telephone while operating a vehicle by drivers with a learning permit or provisional license (makes exceptions for emergency/911 calls).
Mississippi
 HB 1551 (2002): prohibits local governments from passing restrictions on mobile telephone use while driving.
North Carolina
 SB 1289 (2006): prohibits the use of a mobile telephone while operating a vehicle by drivers under the age of 18 (makes exceptions for emergency/911 calls).
Oklahoma
 HB 1081 (2001): prohibits local governments from passing restrictions on mobile telephone use while driving.
Tennessee
 HB 564 (2003): prohibits the use of a mobile telephone while operating a school bus.
SB 36 (2005): prohibits the use of a mobile telephone while operating a vehicle by drivers with a learning permit or provisional license (makes exceptions for emergency/911 calls).
Texas
 SB 1257 (2005): prohibits the use of a mobile telephone while operating a vehicle by drivers under the age of 18 for the first six months after license is issued; prohibits the use of a mobile telephone while operating a school bus.
Virginia
 SJR 336 (2001): requires the Department of Motor Vehicles collect statistical data regarding the dangers imposed by “distracted drivers.”
West Virginia
 SB 219 (2006): prohibits the use of a mobile telephone while operating a vehicle by drivers with a learning permit or provisional license (makes exceptions for emergency/911 calls).