I used to think it was such a clever social manipulation back in college; Professor Pausch (yes, that one) would show his cell-phone to his audience and remark how advanced & marvelous our technology is. “If you would all show me yours as well….. then we can turn them all off right now.”
Har har. It worked, his lectures were ringtone-free.
More commonly, I’ve seen his sentiment echoed ironically today; “I have only one rule for my talks, if you have a cell phone, please take it out, and twitter/blog/talk about this, using the hashtag #yaddayadda”