twhirl is a desktop client for the popular microblogging service Twitter. It allows you to post short 140-character updates about what you are doing, as well as following your twitter friends and read all their updates, replies anyone sends to you, and direct messages to your account. You can also answer to another user by replying or sending him/her a private direct message.

twhirl has a lot of other features, for example looking up other user’s profiles, searching public tweets (powered by terraminds, favoring tweets etc.

The latest version added support to post your updates to two other services, Pownce and Jaiku.