Need to change domain name in WPMU

http://wpmututorials.com/how-to/change-the-domain/
http://www.kristarella.com/2009/05/how-to-move-wordpressmu/

Changing domain name AND moving to a different server will be an involved process and there are different ways to do this. Others prefer to make the domain name in old server’s database which is risky. While others including me prefer to change or import revised sql with new domain name in new server’s database.

Don’t forget, you will have to make domain change in wp-config.php backup and also check the htaccess backup as well if needed.

For further assistance, go to WPMU forums – http://mu.wordpress.org/forums/