I would simply like to add that I believe most people in the public rarely consider how many things our officers have to do at the same time while they are on the job.
While the distraction of trying to talk/listen on a phone while driving is a very real concern, it does seem to me that most people in the public who are engaging in the practice have likely never undergone any kind of specialized training to learn how to multi-task at this level... at most it's a skill that they've acquired through long hours of personal practice. However, even before police carried cell phones, specialized training in multitasking was a necessity. They have to be able to monitor their radio traffic - sometimes on more than one channel at a time, observe their envoriment in detail (details that they also have to be able to reliably recollect later if something that seemed incidental in passing turns out after the fact to have been important), and still operate their vehicles to a standard of safety and responsibilty that should exceed that of a casual civilian driver. Adding the cell phone into the mix is probably a drop in the bucket by that point...
At any rate, that's my perspective...you may see things differently ; )