I'll begin by directing you to an article in The Star.com (thanks, tlev), Tweet, tweet - there's been an earthquake, which states:
"A little over a year into its life, Twitter appears to be reaching its tipping point – the threshold where mindless pastime ends and social relevance begins."And it describes how "tweeters" alerted the world to the recent earthquake in China before anyone else. Another practical use of twittering (tweeting) can be read in Andy Carvin's Waste of Bandwidth: Almost Arrested for Taking Photos at Union Station in New York City.
which describes how this NPR photographer was hassled and banned by security guards:
Just got told by security to leave. Asked to speak with a supervisor to explain why we can't take pictures at union station.But the best use of twittering so far must be this tale from Egypt: How to use Twitter to get out of jail - where the one word tweet "Arrested" spoke volumes, and saved the tweeter's ass from jail. (Not so lucky was his non-tweeting translator.)
For tweeting to work most effectively, a mobile phone with text capabilities is absolutely necessary. Otherwise you're limited to computer-only, like me (until I upgrade my phone plan.)