In anticipation of the Wrath of the Lich King launch this Thursday, Blizzard has opened up a brand-new US PvE realm called Fizzcrank. Some of the higher-population realms will be eligible for transfer, presumably in an attempt to lower populations so the realms don't crash and burn in a few days. So far, according to the breaking news box, players on the following realms are permitted to flee:
That list comes suspiciously close to the beginning of the alphabet, though, so I wouldn't be surprised if it's a truncated portion of a bigger list. Blizzard is saying to go to the account management page to check if you're eligible. Also no word yet on what battlegroup Fizzcrank will be a part of. Stay tuned for updates.