The Twitter online interface has just received a makeover with a sidebar with extra information for users.  You can now see info, like individual tweets, user's profiles, photos and videos as well as various "media providers" that you can now see inline.

Other new additions include keyboard shortcuts and unlimited scrolling of one's Twitter stream.

It will launch for a group of selected Twitter users and the rollout will be incremental.  The new addition will be supported in all languages but no one knows how long it will be before everyone gets it.