I recently decided to reinstall my WordPress blog with the SVN copy of the software. Because WordPress does not support upgrading through the default install- a major hindrance, I've decided to keep my copy updated through SVN. This means that you need a working copy of SVN on your server. If running Ubuntu/Debian, the following command will get it installed (assuming your account is added to the /etc/sudoers file:
aaron@kratos:~$ sudo aptitude install subversion
Once installed, all you need is to get the latest copy to your server in the directory that you plan on serving it from. For example, if you plan on serving it from /var/www (also, assuming your unprivileged account has write access to /var/www):
aaron@kratos:~$ cd /var/www aaron@kratos:/var/www$ svn co http://svn.automattic.com/wordpress/trunk/
Now you have the latest copy of WordPress running on your server. Configure your web server daemon as needed to serve PHP files from that directory. When ever you need to upgrade, just issue an 'svn update' on that base directory:
aaron@kratos:/var/www/trunk$ svn update
There you have it, the latest and greatest running copy of WordPress. Of course, it should be warned that this is the unofficial release of the software, and bugs may exist causing problems with plugins and serving the software. However, if you are willing to take the punches, then I would recommend running the SVN copy to keep your WordPress insall up-to-date. Until the WordPress devs decide it's important enough to add an upgrade utility in the software directly, this is definitely the best approach I think.