Blizzard made the following announcement today regarding character transfers.

Two More Character Transfers
We have opened up the next round of character transfers with Frostwolf to Frostmane and Ner'zhul to Crushridge. This brings the total number of available transfers to five.
Below is the list of currently eligible and upcoming realm-to-realm transfers. We'll make another announcement here when realms in the second list below become eligible for transfers. Alternately, you can visit our new Changing Realms page, available after logging in to account management, to see the list of realms that are currently eligible.

If you wish to participate, visit our Character Transfer page to start the process! We expect that transfer between the currently eligible realms will be available for approximately two weeks, and we will post another notice here prior to their closing.

ELIGIBLE TRANSFERS

Blackrock → Bloodscalp
Icecrown → Azjol-Nerub
Deathwing → Stormscale
Frostwolf → Frostmane
Ner'zhul → Crushridge
UPCOMING TRANSFERS

Proudmoore → Dragonblight
Silvermoon → Draenor
Archimonde → Firetree
Kil'Jaeden → Boulderfist
Tichondrius → Dunemaul
Doomhammer → Perenolde