Michele at A Big Victory writes a great open letter addressing the lack of common courtesy and decency on display at just about every public event one attends in this day and age.
At some point in the future, I really believe that people will come to the conclusion that cell phones have done more damage than good in modern society. The only solution to the problem that Michele describes is a "cell phone check," akin to the coat checks of yesteryear. Just take them away at the beginning of the event, and give them back at the end. If "social networking" is more important than the event, then you probably should not have come in the first place.
I realize that cell phones are just one manifestation of the decay in public behavior that seems to be advancing at an alarming rate (and I also realize that I sound like an old curmudgeon for writing all of this), but you have to start somewhere.