How To Enable Multiple Site Network Options Like WordPress MU in WordPress 3.0

I recently acquired WP 3.0, Buddypress, and the BP Daily Theme. I want to have multi site functionality. I read on a website called http://www.clickonf5.org that I must make code changes in WP 3.0 to have the network function. Is this true?

They suggested the following:
"Open wp-config.php from the root folder of the domain where you have installed WordPress 3.0 and add the below line of code before this line “/* That's all, stop editing! Happy blogging. */:”

define('WP_ALLOW_MULTISITE', true);"

Do I net to do this to have MU functionality?