The problem isn't so much with talking on
cell phones in general as it is with the
distraction wrought by the
peculiarities of the device itself.
Cell phones involve an awful lot of technology, but the part that's most important to this discussion is the keypad. Punching numbers into a keypad drains attention that needs to be spent concentrating on the road.
The second problem is that you have to hold a cell phone up to your ear. This is bad because if you suddenly need to apply two hands to the steering wheel, you have to drop the phone, which takes precious seconds. Hesitation can make it worse. If you are driving a stick, forget about it. The sensation of having the phone next to your head may also sap attention. (Intangible, I know, but I'm sure you know what I mean.) I know people who not only talk on cell phones while driving, but actually send e-mail from them. One of my friends sent me an e-mail about how he was listening to Cruel Summer and typing out a message on his RIM e-mail pager, all while driving down the freeway. I don't have anything against Bananarama, but that's just lunacy.
The solution is twofold.
Many newer cell phones sport voice recognition. You can program numbers into them and then say a word, which the cell phone will recognize in the future (for example, "Vinny"). This eliminates the need to punch in numbers or scroll through a list. So, the first solution is to get a phone with voice recognition.
The second solution is to use hands-free operation. Virtually every cell phone sold today either has an optional earpiece/microphone, or has speakerphone capability, such as the Motorola i1000s used by NexTel. I would recommend getting a cell phone with speakerphone capabilities, so that you don't have to wear a rather silly-looking accessory whenever you are in the car.