Ask HN: Methods for reserving and verifying celebrity usernames?

Twitter indicates that some accounts really belong to the specified celebrity via "Verified Account" badges, but they indicate that they are "closing the beta test of this feature to build a system that will be better for users.": http://support.twitter.com/groups/31-twitter-basics/topics/111-features/articles/119135-about-verified-accounts

When Facebook offered vanity URLs, they had determined a list of celebrity-reserved vanity URLs before the vanity URL requesting service went live.

Is anyone familiar with how major social networking and other sites got their list of "celebrity usernames" or whether there is a list currently available and updated online or available via some other method? How about the process that sites use to verify that people are the celebrities that they are claiming to be? Do you have any suggestions for those wishing to avoid future issues on their site by having a (hopefully lightweight and low-cost) celebrity username reservation and validation process in mind from the beginning?