So you have your Multisite set up all nice, you have got rid of all those advertising icons and phrases telling your customers they could get the same thing from WordPress.
Ohh but wait!!!
WordPress 3.1 adds a new point of advertising for your users to see. Yup, when you create a new site they will get that Welcome Panel, you know, the one you also received.
1). Dig right on into the code and find more of those references. (Edit it to your needs, so its your own welcome panel)
2). Dynamic text replace - https://premium.wpmudev.org/project/site-wide-text-change
3). Edit the wp-admin/index.php file and remove:
<?php wp_welcome_panel(); ?>
4). Use that plugin provided by Andy Nacin - http://wordpress.org/extend/plugins/hide-welcome-panel-for-multisite/
No more admin panel and more ways for WP to advertise to your customers and users.
Thought this might help someone.