Twitter’s march towards world domination continues apace. This morning comScore released its global numbers for March, 2009. Worldwide visitors to Twitter.com increased 95 percent in the month of March from 9.8 million to 19.1 million, according to its estimates. This compares to 9.3 million visitors in the U.S. alone. …
If Twitter can keep this rate of growth up, it should cross 50 million visitors by summer.
TechCrunch – Twitter Eats World: Global Visitors Shoot Up To 19 Million

Twitter is cryptic and useless for most people.
Avoid it if you can. (Though you might want to grab a twitter name now, while there are still many availlable, just in case.)
I have:
https://twitter.com/besthike http://twitter.com/GymCoaching http://twitter.com/McCharles
Actually, once you follow 50 or more people, it can be interesting. I’m starting to like Twitter despite its many failings.
I have not started using any of the Twitter clients, as yet. But I’m leaning towards trying Seesmic Desktop.