Twitter refreshes iPhone app interface, adds new Tweet composer, notifications when friends sign up

Twitter has updated its application for the iPhone and iPod touch with a refreshed user-interface for the Tweets timeline.

Additionally, the updated application features a new Tweet composer interface that actually allows users to preview what a posted Tweet will look like in the timeline. Also notable is the new ability to receive notifications when friends join Twitter.

Improvements and fixes for the Lists functionality are also present in this 5.7 update.