Well birds twittered back then, but...
The point is that Amy Vanderbilt's etiquette book never contained a chapter about the etiquette of technology in a hyper-unfocused world. She never told us that it's impolite to text during a conversation, so we have to figure it out ourselves. And it's taking a long time, since the world is a lot more distracting than it was in the 1950s.
I think that my generation has to learn to look at the logic of etiquette before we start memorizing how it works in individual applications. The point of etiquette is to put people at ease. This is accomplished by establishing common rules for behavior, and by acting in a way that's generally predictable (that is, one would expect a visitor to sit on a couch as opposed to jumping on the couch and yelling profanities). Based on personal observations, my generation is sometimes confused about what it means to put people at ease.
So I'll use the example of texting during a conversation. The reason it's bad etiquette to pick up a cell phone and start texting while your friend is in the middle of a sentence is that it will make the speaker feel unimportant. Obviously, you like whoever is texting you more than you like the person who's speaking to you in person. ;) If you've ever been in a situation where one of your friends abandons you to go talk to another friend, you'll know how uncomfortable it is to be given the message that you're the "gamma" friend. Abandoning a friend for a cellphone is pretty similar.
Granted, we all have a hard time breaking ourselves away from technology. It's addictive, and it's almost a pavlovian response that we experience when we hear our phones beeping. We have to keep reminding ourselves: people. Pay attention to people. Be aware of what they're saying. Cell phones can usually wait. People, however, don't enjoy spending their time watching others compose text messages.