Twitter comes to Ubuntu by default, in Lucid Lynx.

The new version of Ubuntu will be having Gwibber installed, a new social client that allows you to connect to

• Twitter
• Flickr
• StatusNet
• Qaiku
• Facebook
• FreindFeed
• Digg
• Identity.ca

Gwibber is already included into Alpha releases of Ubuntu 10.04, and it is a very simple and efficient client. It's easy to be configured, starts fast, moves fast, and it's easy to see your own tweets in the timeline.