So some things have changed in WordPress 3.0. While some of us don’t mind having a link to the wordpress.org website in our blogs and sites, many people are putting together sites for clients and they can’t have those links in place. So what do you do?
The file you need to edit is /wp-includes/default-widgets.php
Go to about Line 300 and you will see this line (in the picture highlighted in blue. Click it to blow it up)
Delete that line, save it, and you are done. No more wordpress.org in your sidebar! Yay!