Ahh....today's youth

Could someone please fill me in on the proper etiquette for dealing with these young people and their Star Trek communicators?
My first instinct when they are typing away on these things like Izzy Stone is to keep quiet.
I don't want to be rude. I'd hate to interrupt what is evidently an important uh...conversation?
I'm not even getting in to the whole "Time and place for everything" aspect of this.
These youths, and by "youths" I mean the 20somethings, have apparently lost their social graces.
It's not really their fault though.
I mean, they've been told they need all this technology and like good little sheep they comply.
Really, how did we ever live without it?