ArenaNet has posted on their blog reminding people that character names from Guild Wars 1 ("classic Guild Wars") will be reserved for Guild Wars 2. However, names will only remain reserved until the official release date, at which point they become up for grabs.
The blog post makes it clear that the list of reserved names has to be created a few weeks before release and it will only contain names from accounts that have logged in after January 1st, 2012. Since characters in classic Guild Wars have at least two word names, all possible one word names players could think of will be available from the 3 day headstart access.
So how do players reserve their character name? Login as soon as possible before ArenaNet builds their reserve name list and create your uniquely named character during the "three days of headstart access". Once any name is taken, players will hold that name across all the servers.
So login and remember to make all your characters as fast as you can at pre-launch.
I know I will.