This is a great article on the different ways to approach Twitter: http://mashable.com/2009/04/20/twitter-strategy/
Personally, I’m against using it as a personal status updater. Why limit your personal status to 140 characters when you have a Facebook account? Or your own blog? There are so many more methods of getting out what you’re doing this very instant much more effectively, and Twitter will not survive as a fad for long if more and more people use it in this very way (and they are).
My unfortunate prediction for Twitter is the following: Although it will remain useful as a means for professionals in certain industries to communicate effectively, it will die as a fad within a year. Growth has been extremely high recently, given the popularity given to it by certain celebreties (Opera, Ashton Kutcher, etc.), however these new users are almost all using it as a limited Facebook status. They will use it for a month, and slowly move on to other things and forget about it entirely. It’s just the nature of things, but mainly the nature of fads. Harumph.