Recently we upgraded Goelji.com to WordPress MU 2.7. And, along came some

In WordPressMU 2.7 there is a new admin bar. It has settings so users can see it on the admin panel side if they are logged in, and a wonky bit to switch between blogs that may have a few bugs.

For any reason if you don’t want it then here’s how to disable it.

Go to wp-config.php (you will get it where you installed WordPress MU). Edit it.
Find the following lines in wp-config.php

// Uncomment to disable the site admin bar
//define( ‘NOADMINBAR’, 1 );

In a freshly installed copy of WPMU 2.7, you’ll find these lines in wp-config.php when WPMU is up and running.
In case of upgraded WPMU 2.7, check the config-sample.php and make sure you copy these lines into your existing wp-config file.