Facebook will make available readable usernames (rather than IDs) starting on Saturday on a first-come first-served basis. The description of the new feature is in the Facebook Official Blog, "Coming Soon: Facebook Usernames".

The usernames countdown site is at: http://www.facebook.com/username/. The feature will become available "Starting at 12:01 a.m. EDT on Saturday, June 13", that is 6 am European site. The countdown page will show the time at your current location.