Twitter is a website where you can post things.
Just one more blog ? Not really …
First, you can update it via the web interface, of course but also via IM (AIM, GTalk, Jabber… more to come !) or even SMS.
Second you can get updates of your buddies via the same.
Third, the updates of your friends can be subscribed in your newsreader via their news feed (RSS)
This is getting connected 
[...] My old post about twitter [...]
[...] you don’t know yet about Twitter, you might want to have a look at my previous article about it. One of its neat features is the (previously written about) ability to send direct messages to your [...]