Back in the day, there were two flavors of the WordPress blogging platform: WordPress and WordPress MU (Multi-User). With the release of WP3, these two versions have been merged, but the MU functionality is hidden by default.
If you’d like to create a multi-user blog, you can edit wp-config.php to enable MU support. Simply add the following line of code:
Next, save the file and then reload the WordPress Dashboard. You should now see a new “Network” tab under the “Tools” menu. This is where the magic happens.
Note that, while it’s technically possible to convert an existing WordPress install to Multi-User format, this is most easily done with a fresh install on a new site.
I still haven’t done this myself, but have considered creating a multi-topic blog using the multi-user functionality. I’ll be posting more in the future on this topic if I decide to go this route.