The Twitter app for the iPad has been rebuilt from the ground up. According to the official Twitter blog, version 5.0 is "fast, beautiful and easy to use." The update brings expandable tweets with in-line photos, new Facebook-like header photos, the ability to track interactions with other people, and other improvements and fixes.
However, the new version also removes the ability for users to share photos using third-party services. Instead, users must use Twitter's Photobucket powered service. The move is part of Twitter's attempt to deliver a more "consistent" experience to its subscribers.