It still happens, but anecdotally it's dropping and fast. In the last couple of years we've seen people actually
turn against such behavior, and that's the first step. Like another poster brought up, you don't hear phones ring in theaters any more - it took time, but the new etiquette is catching on.
> "They are a tool of social disconnection"
Balderdash. On the whole smartphones have been a net gain for socialization. Remember, certain people also lamented the loss of the hand-written letter, or the telegram, and predicted grave consequences for the nature of human interaction. None of which has come true. The need for social contact in humans transcends any technological imposition we can place upon it.
Look at Facebook, which is a favourite whipping boy of HN's, but they have changed the face of socialization. You are now capable of keeping up with many more people than ever before - and I call shenanigans on people who would claim this form of interaction is "cheating" (like a rolodex is cheating), or somehow less genuine (elitist bull).
To pre-empt an incredibly facile and common argument that relates to this: keeping up with more people is a good thing, and the whole notion that having fewer, tighter friends is unequivocally better is arrogance in the extreme, not to mention a huge case of false dichotomy.
So, back to smartphones. It has enabled a new, lower-barrier-threshold communication form (SMS/IM) that is not as intrusive, it has enabled incredible ability to keep in touch with a category of acquaintances which previously got no attention at all (Facebook/G+/etc), it has given us tools by which organizing large events is easier than ever before (GroupMe, Facebook), and finally realized the dream of vid-calling (FaceTime/Skype), as well as the tools by which we stay informed about important news of relevance to our daily lives (Twitter, Facebook), and hell, it's even helping us make friends and date (Meetup, OKCupid, Match, etc, all of which have deep mobile integration).
So what's that about smartphones been a net negative again?