Twitter is similar to your facebook status in 140 characters or less. Some call it microblogging. I find it annoying and useless but I go through spurts where I update it frequently.
Similar to friends on facebook, you can follow other twitter users and see what they're saying at any given time. Upon signing up, I immediately started following some of the more prominent people in the law and technology field. Three or four of them quickly polluted my account with tons of inane nattering. Most of it seems to be notifications of new blog postings and "interesting" links. Since I already follow their blogs through RSS feeds, most of this is redundant and it drowns out the updates from people I've actually met or care about following.
A friend of mine used twitter to provide updates while he and his wife were expecting. It got a little weird when his wife went into labour.
Contractions are quick and regular. Off to the hospital.
5cm dialated
10cm
I can see the head!!!
The placenta is bigger than I expected
I used to use twhirl on my desktop to stay in touch with twitter but it kept pestering me with updates from the inane people noted above. I installed twitterberry on my blackberry in order to update my own account. It's fast, it's minimialist and it works pretty much all the time. Of course, none of the stuff in my tweets is of sufficient importance that speed becomes of the essence. And none of the people that follow me care enough about twitter (or me) to anxiously await the latest updates anyway.
In case none of this blathering sells you on twitter, here's how Steven Matthews (one of the inane twitter users described above) explains twitter:
http://www.stemlegal.com/strategyblo...-with-twitter/