Your posts to twitter with more than 140 characters will be posted instantly as multiple tweets and in correct order. Put in as many characters as you need to. Search twitter, message friends, browse your home timeline, and respond to all of that with more than 140 characters (again, will be turned into several tweets).
Great for:
Tweeting entire chapters from your young adult novel
Tweeting an entire blog post from your site
Tweeting an entire recipe
Tweeting US Politicians the entire US Constitution