The current version of WordPress MU has now been merged with the current WordPress track. Information about current and future development versions of WordPress, with MU capabilities, can be found under the topic of Tracking the WordPress Trunk.
NOTE: Code from the WordPress trunk is often untested and sometimes has bugs. It is not recommended for production installs.
Subversion is server-side software and must be installed on your server before continuing.
Subversion is a versioning tool. At the most basic level Subversion will update the code on your WordPress installation with the latest code from the WordPress repository.
The checkout command is used for installing a fresh copy of the software from the repository to your server, and is used for the first install. The switch command is used for upgrading.
For a fresh install, use the checkout (shorthand: co) command to install a fresh copy of the software onto your server.
Early in WordPress 3.0 development, the WordPress MU project was merged with the WordPress Project. If you wish to get the latest version of WordPress, with mu features, from the SVN Repository, follow the instructions for Tracking the WordPress Trunk.
To get a fresh copy of the most recent tagged version from the repository (go to http://svn.automattic.com/wordpress-mu/tags/ in your web browser to search for the latest tagged version):
The switch command is used to revert the code on your server to another version of the code. In this case switching from an older version of the code to a newer version.
Reference guide for switch command: http://svnbook.red-bean.com/en/1.4/svn-book.html#svn.ref.svn.c.switch
The procedure for WordPress core code is the same for plugins hosted at http://wordpress.org/extend/plugins
For more information on using Subversion: