During the last week, I've learned to use Twitter. Of course, there is not a lot to learn as Twitter is a really simple system. Consequently, it can easily be updated from the Linux command line without using any dedicated application or a bloated web browser. You just need to have curl installed on the system to use the following command:
curl -u "username:password" -d "status=here comes the status update" http://www.twitter.com/statuses/update.xml
And to make it even simpler, you can write a simple script to send the updates from the command line:
echo "Twitter update: $1"
curl -u "username:password" -d "status=$1" http://www.twitter.com/statuses/update.xml >/dev/null
After saving the script as tw I made it executable. Now I can send updates with:
tw "This is my update"
If you intend to send a lot of tweets from the command line, you should probably add some sanity checks to the script.
Edit: I added >/dev/null to the end of the third line in the script in order to reduce the amount of text output.