Drupal released their first beta of the next version of Drupal called 5.0
Some significant changes including a new core theme and a web installer for making it easier to install Drupal. Lots of performance updates too!

http://www.drupal.org

completely retooled the administration page

• /admin now contains an administration page which may be themed
• reorganised administration menu items by task and by module
• added a status report page with detailed PHP/MySQL information

added web-based installer which can:

• check installation requirements
• automatically generate the database configuration file
• install pre-made 'install profiles' or distributions
• import the database structure with automatic table prefixing be localized
  

System

• added new default Garland theme
• added color module to change some themes' color schemes
• included the jQuery JavaScript library 1.0.2 and converted all core

JavaScript to use it

• introduced the ability to alter mail sent from system

module system:

• added .info files for module meta-data
• added support for module dependencies
• improved module installation screen
• moved core modules to their own directories
• added support for module uninstalling
• added support for different cache backends
• added support for a generic "sites/all" directory.

usability:

• added support for auto-complete forms (AJAX) to user profiles.
• made it possible to instantly assign roles to newly created user accounts.
• improved configurability of the contact forms.
• reorganized the settings pages.
• made it easy to investigate popular search terms
• integrated urlfilter.module in filter.module

block system:

• extended the block visibility settings with a role specific settings.
• made it possible to customize all block titles

poll module:

• optionally allow people to inspect all votes.
• optionally allow people to cancel their vote.

distributed authentication:

• added default server option.
• added default robots.txt to control crawlers.

database API:

• added db_table_exists().

blogapi module:

• 'blogapi new' and 'blogapi edit' nodeapi operations.

user module:

• added hook_profile_alter().
• e-mail verification is made optional.
• added mass editing and filtering on admin/user/user.

PHP Template engine:

• add the ability to look for a series of suggested templates.
• look for page templates based upon the path.
• look for block templates based upon the region, module, and delta.

content system:

• made it easier for node access modules to work well with each other.
• added configurable content types.
• changed node rendering to work with structured arrays.

performance:

• improved session handling: reduces database overhead.
• improved access checking: reduces database overhead.
• made it possible to do memcached based session management.
• omit sidebars when serving a '404
• Page not found': saves CPU cycles and bandwidth.
• added an 'aggressive' caching policy.
• removed the archive module.

upgrade system:

• created space for update branches. forms API:
  
• made it possible to programmatically submit forms. improved api for multistep forms.
  

theme system:

• split up and removed drupal.css.
• added nested lists generation.
• added a self-clearing block class.