Blizzard CM Bornakk announced that the following free character transfers will be available from Wednesday, February 13th at 12:00 p.m. PST until Wednesday, February 20th at 12:00 p.m. PST. Of course, these times are fully dependent on Blizzard reaching their transfer goals.
For the PvP servers, you can move from Illidan, Mal'Ganis, Skullcrusher, Smolderthorn, Tichondrius, and Warsong to the Anetheron server.
For the PvE servers, you can move from Aman'Thul, Dath'Remar, Khaz'goroth, and Nagrand to the Caelestrasz server.
Be sure to move as soon as possible! The transfers have been known to shut down early when Blizzard reaches their goals.