I agree with all of the above except the video store comment. I think that IS a most appropriate use of cell phone.
I was at McD's with a friend to satisfy a horrible late night craving (Oh, come on now don't tell me it never happens to you! ) and the french fry girl was texting away then touching my food, and I thought of how absolutely filthy that phone must be. Why don't you handle my money too, it's probably cleaner than that electronic Q-Tip!
Once in a while I'll do talks at various events and a cell phone rings and some idiot actually answers. I stop, smile and wait for the call to be over. Because I'm so polite (artifically so), they usually get the point and it doesn't happen again. Next thing I know everyone is checking their cell phones. But then again, we're Canadian up here!