WordPress 3.0 introduces several new multi-site features including the ability to host unlimited sites and users from a single WordPress install. It can be installed with sub-domains or sub-directories and requires PHP 4.3 or greater, MySQL 4.1.2, and Apache mod_rewrite. Upgrading from earlier versions of WordPress MU to 3.0 involves replacing files and modifying the .htaccess file. The presentation also covers deprecated functions, code backups, and database backups.