@matthewcornell asked "do you use Twitter for personal updates (I'm at the __) or quotes/information, or...?"
A few thoughts. Just yesterday my wife Liz and I were talking about this. I had set up Twirl on her computer so she would see my tweets and I also signed her up to follow a few other people I thought were interesting. These included @pearlbear who Liz doesn't know and who I only know via friends (though I think I've met her once). Liz remarked how strange it is that she now is following @pearlbear's move west across the country and she doesn't even know the woman. Twitter does produce a different kind of intimacy. People wonder if produces a somehow "false" electronic intimacy. In my opinion, any kind of connection between people is good. Twitter is a way to be connected to the lives of more people, more easily and what can be wrong with that?
Twitter does seem to divide between those who use it to connect personally with each other, both around ideas and around time and space ("headed to the coffee shop at Main and Hope"), and those who use it to pass tidbits of larger relevance back and forth. For my part, I tend to be following people who provide quotes and links valuable for my work such as @pkedrosky. When I joined Twitter I was amazed at how much more effective it is than other social networking systems at producing serendipitous connections to work-relevant people--for example the connections to the mobile-devices-for-good-crowd I know follow because of @Katrinskaya. Partly this is because you can follow people without the question of whether "friending" them is appropriate or not. There's a low bar to following and deleting a follower. I also follow those on Twitter who aren't work-relevant but are simply intersting, producing their own brand of haiku such as the irreverent and seemingly often drunk @warrenellis. Example of his latest: "Suck it up, hippie. Sarah Palin could break your limp wrist simply by flexing her womb. You Yank owl-huggers are in for it now."
Main point, that's been made by others: the Twitter limit of 140 characters forces a beautiful economy of language. If you can't say intriguing, relevant and catchy things within that limit, you're mundane and not worth following. A great practice for those working up to pitch movies or ventures, actually. Or those who need to be on TV or radio and come up with soundbites.