What's Changed? Like any upgrade, WordPress 3.0 brings a laundry list of new features. Many of the changes are under the hood and unlikely to be noticed by anyone other than developers. The features to watch in 3.0 are custom menus, custom post types and taxonomies, a new default theme and improvements for customization, and integration of WordPress MU.Although WordPress was initially envisioned as a personal blog platform, it's been extended to handle all types of publications. In recognition of this, the project has finally provided custom post types for 3.0. If you want to use WordPress to publish material that doesn't fit neatly into the post or page classification, you can use custom posts to handle the overflow. Again, as shipped, WordPress 3.0 doesn't make this entirely easy. The default install doesn't include a user interface for creating custom post types. Luckily, the community has stepped up to provide the Custom Post Type UI plug-in. This streamlines custom post creation from the UI. Even with the plug-in, it takes a bit of tweaking and experimentation to create new posts. Alongside the custom post feature is the custom taxonomy feature. Taxonomies are a way to further categorize posts or other content. The default taxonomies for WordPress are the category and tags for posts. You can use a taxonomy to help define other content, such as custom posts. With the Custom Post Type UI plug-in, it's easy enough to implement new taxonomies for the small percentage of sites that require them. The new default theme is a bit nicer than prior WordPress themes. Users can easily tweak the new theme with their own header graphics and add custom content menus. Aside from the theme and content menus, not a lot has changed for users in the WordPress UI. Version 3.0 doesn't bring any radical redesign or massive new end-user features. The post editor is virtually unchanged, and the general layout and features of the Dashboard remain the same.
The WordPress project has been offering WordPress MU for some time as an option for publishers or organizations that need to host a large number of blogs on a single WordPress codebase. It's easy enough to host two or three instances of WordPress, but after that you run into problems with administration. With 3.0, the project combines the multisite capabilities into the standard WordPress install. Almost, anyway. Multisite support is not actually enabled out of the box, and requires a few tweaks to the wp-config file and some other adjustments.