Facebook recently announced that effective as of 12:01AM, this Saturday June 13, 2009, it will be possible to register a Facebook username (including trade-marks) as a URL (for example: facebook.com/your trade-mark).
As of that time, registration will be available first-come, first-served. This means that Facebook users will be able to use the trade-marks of third parties as their usernames.
Facebook provides the possibility for rights holders to prevent this situation by allowing them to fill out an electronic form (the “Preventing of Registration of a Username form”) available at: http://www.facebook.com/help/contact.php?show_form=username_rights
After a username has been registered rights holders may also alert Facebook of an infringement of their intellectual property rights by filling out an “IP infringement form” available at: http://www.facebook.com/copyright.php?noncopyright_notice=1
For more information you may visit Facebook's FAQ section at: http://www.facebook.com/help.php?page=899