Troublemaker Eugene Volokh believes that you have just as much right to talk to someone over the telephone as you do in person! Critiquing Robin Wallace’s idea that it’s bad to discuss personal business in public, Professor Volokh distinguishes between rudeness (talking during performances or concerts) and simple discussions with friends or family:

Now back to the first two paragraphs (and setting aside the conversations in the yoga class and the dinner party, which I agree are generally rude, setting aside extenuating circumstances). Imagine that the writer had been sharing a cab with two other people, who were saying the same things to each other in person, or overheard two people conversing in the gym or the grocery store. Would he have said that it was rude for them to talk to each other? Well, maybe, if they really were quite graphic in dicussing their sex lives. But I had never, until the advent of the cell phone, heard of people complaining “I was on a bus — or at a grocery store or in the gym — and two people were complaining about their creepy bosses and their financial woes; how rude!”
Talking to a friend in public is generally seen as perfectly well-mannered behavior, if one isn’t too loud, one isn’t socially obligated (or, in the case of driving, obligated by the needs of safety) to pay attention to others, and one stays away from a small set of extremely private topics. In fact, it’s often thought of as good — instead of shopping or riding in solitude, one gets to socialize with a friend. As a matter of manners, I don’t see any reason why the rule should be different when one is talking on a phone to a friend who’s physically absent.

Volokh’s a man after my heart, and not only did he remind me of a previous post, he also reminded me of an incident at a local shopping center which might shed some light on the emerging anti-cellphone mentality.
There I was, staring intently at one of those huge display maps, trying to figure out the location of particular store when my cell phone rang, and I dared to answer it. Lo and behold, it was Justin, and yes, I confess, we dared to chat. At some point, an issue in the blog came up (I can’t remember what, but it wasn’t especially earthshaking), and while I was talking, a total stranger walked right up to me and snapped, “ARE YOU TALKING TO YOURSELF?” Nonplussed, my reaction was to say “YES! I LOVE TO TALK TO MYSELF!” The guy stormed away, looking even more annoyed, with one of those “there ought to be a law!” looks on his face.
Now, I was wearing an earbud, and I know that this might be confusing to some people, especially the technologically unsophisticated. But I think my earbud is obvious. I have short hair and I make no attempt to hide the thing, and the man who came out of his way to barge into the conversation was considerably younger than I am. He appeared to be in his mid thirties, and was wearing glasses, which meant he could probably see. And he obviously could hear. While it’s all unprovable and speculative, I think he just didn’t agree with what he heard me saying to Justin (which I’m pretty sure was political in nature.) I very much doubt this same man would have come up to me had Justin been there and I’d said exactly the same thing. Nor do I think he’d have been as annoyed had I really been some mental case talking to myself. I think he knew damned well I wasn’t talking to myself, and this was just his way of being rude.
He, of course, would say that it was rude of me (or “exhibitionistic”) to discuss politics. In a shopping center. He’d probably also opine I shouldn’t have been “sharing” my “personal life.”
Not that such a characterization of my conversation would make any difference.
If the personal is now political, then the political must now be personal!
I have some lingering questions. Is it ruder to discuss politics over a cell phone than to discuss “personal” issues? Is it ruder to use an earbud than to hold the phone to your ear? Is the polite thing to crawl into the darkness somewhere and hunch over? This is an evolving area of etiquette and I am not sure. I prefer not to talk on my cellphone in public, but if it rings in a place like a shopping center, if I’m alone I’ll tend to answer it.
Rights are one thing. I was well within them legally. But are there rules?
Bear in mind that I was slow to get a cell phone, as I dislike telephones of any sort because I have problems with interruptions. I do have friends who are possessed of the “I refuse to get a cellphone ever!” mentality, and while I’m somewhat sympathetic, I think they’re making too big a deal out of what is just another way of communicating.