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New features added

• Status page and requirement checking: added a status report page with detailed PHP/MySQL/Drupal information and requirement checking.
• Web-based installer: added web-based installer that checks run-time requirements and that supports pre-made install profiles or distributions with better support for database table prefixes. It is also localizable.
• Core theme: introduced a new default core theme, called Garland (and a fixed width version Minnelli). Garland uses the new color module to change the theme's entire color scheme on the fly.
• Custom content types: core now includes part of the Content Construction Kit and allows you to set up arbitrary types out of the box. For more fields, install the full CCK package from the contributions repository.
• URL filter: integrated the URL filter module into the filter module. This will cause web and e-mail addressed to be automatically hyperlinked.
• Blocks per role: extended the block visibility settings with a role specific setting and retained the option to control blocks by PHP snippets..
• Edit block titles: Drupal 5 makes it possible to customize or overwrite all block titles, even set block titles to empty.
• User management improvements: Added support for auto-complete forms to user profiles. The ability to filter users by role, permission and status to help better manage users. Made email verification of user accounts optional.
• Improved module administration: Modules are listed by category and origin, their versions are displayed, and their dependencies are listed in the module descriptions as required or optional.
• More logging reports: Drupal now provides detailed reports on search terms, 'page not found' and 'access denied' errors to help improve your site.
• CSS preprocessor: All (cacheable) stylesheets are now aggregated into one compressed file, which makes your site faster, especially for first time visitors.
• Performance tuning: Key parts such as Drupal's session and access mechanism have been optimized for faster page loading across the board.

via drupal.org