WordPress 3.0, the thirteenth major release of WordPress and the culmination of half a year of work by 218 contributors, is now available for download announces the WordPress Blog at: http://wordpress.org/development/2010/06/thelonious/
Features:
WordPress and WordPress MU have merged, allowing the management of multiple sites (called Multisite) from one WordPress installation.
New default theme “Twenty Ten” takes full advantage of the current features of WordPress.
New custom menu management feature, allows creation of custom menus combining posts, pages, categories, tags, and links for use in theme menus or widgets.
Custom header and background APIs.
Contextual help text accessed under the Help tab of every screen in the WordPress administration.
Ability to set the admin username and password during installation.
Bulk updating of themes with an automatic maintenance mode during the process.
Support for shortlinks.
Improved Custom post types and custom taxonomies including hierarchical (category-style) support. (Try the Custom Post Type UI or GD Custom Posts And Taxonomies Tools plugins to see the possibilities.)
A lighter admin color scheme to increase accessibility and put the focus more squarely on your content.
More info at: http://codex.wordpress.org/Version_3.0