Or you could just turn it off.

Oh, I sure did. That’s right. “Cell phones have saved more lives than antibiotics” were my exact words. You can look it up.
Look, to anyone with a functioning brain cell, the following things are basically inarguably true:
(1) Cell phones make it easier for people to communicate with each other in situations in which it was previously difficult to communicate
(1a) For certain people and situations, this can be extremely objectively useful. At its best, this can, and does, save lives, by allowing emergency personnel to be quickly contacted. Aside from that, it allows people with mission-critical but not life-saving jobs who are “on call” to go out and do things but be ready to drop them at any time, rather than just go home and sit by the phone, or stay at work for long stretches
(1b) It also allows non-emergency people who are in emergency situations to call 911 without having to find a payphone
(1c) There are also people who do NOT want to be easily contacted at all times. They have the option of not having a cell phone, or having it turned off
(1d) Even ignoring mission-critical and life-saving applications, there are times when it is useful and/or pleasant for joe sixpack to be able to easily contact dave sixpack
(2) As with any new technology, the positive aspects have drawbacks. For instance, if people get dependent on being able to call 911 on their cell phones, then there will be fewer payphones, and someone who has no cell phone, or whose battery has died, might be stuck unable to contact an ambulance
(3) Cell phones also have generated an entirely new category of ways for rude and thoughtless people to be rude. Several new categories. All of which have been discussed in agonizing detail in a baffling number of SDMB threads
(3a) 50 years from now, when cell phones have fully integrated themselves into our lives and the rules and manners for using them have settled down, some of those things will still be rude. Because some people are assholes. Some, however, are due to a conflict between somewhat arbitrary previous rules and new technologies, and new rules will develop, with previously “rude” behaviors becoming accepted. Rules change and society changes.
So, what’s my point? My point is that cell phones have positive and negative effects. Anyone who claims otherwise is off their rocker. Do the positives outweigh the negatives? Well, the market seems to imply so, and I (although I use my cell phone rarely, and almost never for anything other than brief logistical discussions) think so; but if you disagree, that’s fine. But it drives me to distraction that people seem to honestly believe that cell phones have no benefits whatsoever… In another nearly identical thread a few months back, Diosa Bellisima said that she twice had had fairly serious car accidents (I think I’m remembering this correctly) and was able to quickly use her cell phone to call 911. And people basically laughed at her and said she was making it up or lying or something. It was baffling.

(a) That has nothing to do with the example I gave. Calling home from the grocery store and saying “hey, do we need laundry detergent” has nothing to do with catching up with friends
(b) Your argument is circular. Talking on the cell phone in the grocery store is rude. Why? Because it makes you seem like an attention whore. Why? Because you are pretending that you are so important that the grocery store is the only time you can talk to your friend. But only an attention whore or super-busy person would have to talk to their friend while at the grocery store. Why? Because talking on the cell phone in the grocery store is rude.
(c) There are two distinctions you seem unwilling to make, which many other people have made. Do you reject them?
(1) The difference between someone who is basically yelling into their cell phone “MY HEMMORHOIDS! IT’S MY HEMMORHOIDS THAT HURT! WHAT? SHE SLEPT WITH HIM? SHE DID NOT!” and someone who is talking at normal conversational level (or less) into their phone, which someone 5 or 6 feet away would not be able to understand, and not about embarassingly personal things.
(2) The difference between movie theatres and fancy restaurants, where silence and/or quiet conversation is important, and where people are paying good money for a particular experience; versus grocery stores and out-on-the-street, where there is no particular benefit to silence, and where people having a face-to-face conversation with each other would be well within their rights. Why is it OK for me and my friend to go to the grocery store together and talk while we shop, but it is not OK for me to talk at that same volume level on my cell phone while at the grocery store?

Option #1: Dive 30 minutes round trip to go home and get the recipe you forgot to bring.

Option #2: Call wife. Have her read the list to you.

I’m sorry if you don’t want to hear it or not, this choice is easy.

I agree though, bullshit conversations should be done in private.

I have no illusion that what I, or even the majority of people, think of this behaviour is, in anyway, going to alter it. People are going to do what they want.

And we seem to live in a society that prescribes an attitude such as, “I don’t care if everybody around me is annoyed by my behaviour, if people judge me as rude or boorish or an attention whore. It’s a free country I’ll do what I want!” I totally get that. It’s how it is, like it or lump it.

And certainly you and a friend have every right to speak to each other when on the street or at the grocery store. But pairs of people, in any crowd seem to modulate their conversations to the ambient noises in a way that cell phone talkers never do. Yes, from time to time you do actually see a pair of people carrying on a conversation (in person) in loud pear shaped inappropriate tones. Usually these people are teenaged girls/boys seeking attention.

Certainly you have the right to chatter away on your cell phone everywhere you go, it’s a free country. Maybe you’ve got a guy in your town who goes everywhere with a parrot on his shoulder?

I would never try to interfere with his right to do so, it’s a free country, do what you gotta do. But let’s be adult enough to admit that this person is a tad needy in the attention department. And his need for attention is obvious to everyone who sees him. They don’t roll their eyes, or say anything to him, but they know. If you’re having long conversations on your cell phone where others have to hear you, you’re no different.

A lot of landlines will give you the option of setting a ring for a particular caller (or at least someone calling from a particular number). My sister has a specific ring for our mom both on her land line and on her cell. She rarely picks up her phone unless it’s Mom calling, just in case it’s an emergency.

ETA: My solution to this is that the only people who have my cell number are my fiancee, my mom, and my sister. That way, if there’s an emergency and my mom is not calling from home, I’ll still know it’s her (or someone calling on her behalf in an emergency).

Yes, but that is where the ignored problem on the OP comes into play. You expect your cellphone to ring only from people you know and who you trust to judge when to call you. Having it ring from your own cell phone carrier spamming you breaks your system (also the one I use, btw)