Enable multisite feature

Posted on January 29th, 2011

One of the most exciting b new feature of WordPress 3.0 is definitely multisite management. In brief, with a single installation of WordPress you’ll be able to run a network of WordPress blog. How cool is that?

To take advantage of this feature, simply paste the following line of code in your wp-config.php file. This file is located at the root of your WordPress install.

define('WP_ALLOW_MULTISITE', true);

As Andrea_r pointed out, once you added the above code, you have to visit Tools -> Network and set up the network.
Source: http://wptheming.com/2010/03/wordpress-3-0-enable-network/