All a-Twitter: You'll laugh, you'll cry, you'll wonder why - all in 140 characters. it's not just the twords that make Twitter interesting, it's the character limit, the implicit constraint of being interesting, witty, informative - in short, of being worthy of the limited attention of your followers. The best tweets of Twitter [...] are more epigrammatic than newsy. Twitter demands writerliness in a way that instant messages, text-messaging, and even blogging don't. The question "What are you doing" is really an excuse to polish up the tiny moments of life, just as the best writers have always done.
I think most message can say what they need to in 100 characters
140 character limit is ergematic and concise if done with care
Consider the character limit an opportunity to work on haikus.
Which reminds me: Hope everyone knows that AWWW is tweeting, too!