How to change username or page URL on Facebook
So you’ve got a shiny new Facebook page but the address is long and confusing? Well worry no more because you can change it! Just hop on over to http://facebook.com/username and Change your Focebook URL! If you’re like me and manage a few pages, you can also change the name of your pages to a custom URL also! But, you have to have at least 25 active users (Fans) in order to change it.
It’s super simple, but I couldn’t find any documentation on Facebook about it! It seems like this is not a well documented method, and may be subject to change, but I just checked it a few mins ago, (Jan 2010) and it’s working.
The top half of that page lets you change your name, and the bottom half lets you change the name of one of your pages.