The social networking application Twitter has increasingly become a tool for live blogging and journalism. It restricts users to 140 characters at a time, meaning you have to write short. You can Twitter from a cellphone, PDA, or laptop.
If you are interested, read:
Twittering Basics for Journalists
Experimenting with Twitter: How Newsrooms Are Using It to Reach More Users
How We Use Twitter for Journalism
How Should Newspapers Use Twitter?