In the Cataclysm Classic Launch Notes, Blizzard has added a line stating that players will be able to use the portal to Vashj’ir before completing the previously-required quest.
Getting to Vashj’ir
To alleviate potential congestion issues, on launch day we’ve removed a few of the questing prerequisites to use the portal to Vashj’ir that can be found at the Western Earthshrine in the Valley of Wisdom in Orgrimmar and The Eastern Earthshrine near the Stormwind Keep in Stormwind.
Getting Around Azeroth in Cataclysm Classic
Read more on wowhead.com