We had a new IT person thought he could text all-day, He got fired.
Technology's killer blows to etiquette started long ago - when the telephone was invented. How many people, when they're in face-to-face conversation with someone, have the courtesy to ignore the phone ringing?
I agree with Anabelle's comment on the text message while in conversation as it is about giving respect to the person you are talking to, however the example of talking on phone in public place as an example of one conversation being intrusive to others around it could equally be two people talking loud in a public place and the difficultly arrises how quiet do you have to be?