This document summarizes the changes and new features in CodeIgniter 2.0.0. It outlines what has been removed, like scaffolding and plugins. PHP 4 support has been dropped. It introduces new features like Drivers, which allow for parent and child classes, and Packages, which make it easy to distribute resources. Models now extend CI_Model instead of just Model. The document provides tips for upgrading, such as creating MY_Model and MY_Controller files. Finally, it notes that development is now hosted on Bitbucket instead of Subversion.