The World of Warcraft team have confirmed that with the upcoming Warlords of Draenor patch (6.2), they will be releasing sidelined characters’ names back into the wild. Any characters that have not logged into the game since December 7, 2010 will have their names freed up, making them available to anyone creating a new character or using the paid Character Name Change service.

It’s good for large game to do this periodically as many good names can be locked up by totally inactive accounts.

How Do I Preserve My Names?

You will need to log in to World of Warcraft and enter the game using each character whose name you wish to retain before patch 6.2 goes live. While it is possible no one will claim your recently released name and you might be able to snag it again, it is probably not worth the risk if you want to keep your names intact long-term.

Our goal with this great name liberation is to make sure new and returning players have a large and varied pool of names available to choose from—so log in now if you wish to preserve your unused characters’ names for your ongoing journey through Draenor.

The Name I wanted wasn’t freed!

Going forward, we expect to free inactive names around the release of new expansions.  Prior to the reclamation process, we’ll post more information on the timeframe this will occur to allow you the opportunity to preserve your name.

Source.