Just in case you are a late comer…Chris Garrett one of my Twitter friends has written up a great introduction to Twitter aimed at the blogging community but this is also applicable to all of us as well.
Here’s a quick tease of his article:
If you haven’t tried it, Twitter is a kind of online messaging system. It is like a group chat where you post 140 character messages or “Tweets”. You can post links or just text. URLs get converted into TinyURLs if they are beyond a certain length or you can paste short URLs from the service of your choice. WordPress plugins and online services make hooking up your blog feed easy, so every post you make goes to Twitter as a URL.
Just like with other social sites, you add contacts and other contacts add you. Once you have a few followers discussions form. You direct messages to an individual using the @ prefix, eg. “This message is just for @chrisgarrett”. Everyone gets to see these that are following the sender, but these messages appear in the “Replies” tab so you get to see all the replies made to you, regardless of if you are following the sender (optional preference). There is also a DM feature for private messages.