Blizzard has announced a new round of server transfers today and all the information is available here:

Select Character Transfers to New Realm! - Eyonix on 1/26/06
We will be opening character transfers for the 8 realms listed below tomorrow, Thursday, January 26 at 3:00 AM. Characters on these realms will be able to transfer to a new PvP realm, Mug'thol. This round of transfers will be open Monday through Friday from 3:00 AM to 3:00 PM PST until Wednesday, February 1 at 3:00 PM PST. Please be aware that until the transfer window is closed, standard character creation will be unavailable for Mug'thol.

Archimonde
Mannoroth
Warsong
Bleeding Hollow
Skullcrusher
Azgalor
Burning Blade
Burning Legion

Character transfers are available Monday thru Friday from 3AM to 3PM. If you're interested in transferring your characters from the realms listed above to the new PvP realm, please click here.