Starting on February 4th, the millions of Minecraft fans will be given the option to change your in-game name for anyone with a mojang account.
Players will be able to choose any untaken name or make any modifications to their current name. After making the change players will have a 30 day wait period before they can change their name again.
For those still sticking to the first unpaid usernames before Minecraft was available to purchase, their names will not carry over and will be open for selection to new players. Mojang is encouraging anyone with the unpaid names to officially register.
Check out the Mojang account page once the new feature is available.