According to our tipster Gwwfps of the blog Potato Skin, World of Warcraft distributor The9 has manually set all the quests in the Isle of Quel'danas to be fully completed -- that is, all quests on the Isle are now open to all players as though Phase 4 had been opened. With the help of Babelfish, as far as I can make it out, this decision was arrived at to "make up several weeks the partial servers to appear returns to the files question for generally to play the loss which the family brings". If my Engrish serves me right, this means that the move was a drastic resolution to having massive downtime for numerous servers which resulted in realms-wide progression rollbacks. Some servers reportedly had their Isle of Quel'danas progress rolled back several times over the course of one day.
Gwwfps explains it better in his blog, noting that Patch 2.4 resulted in poor server performance across the board. Apparently, WoW China has been suffering from performance issues for quite some time and some have suggested that the servers upon which the game runs aren't quite up to par with Blizzard's standards. Others argue -- with good reason -- that the forced unlocking of the phases makes the game "less immersive." The sweeping measure also demonstrates an apparent lack of industriousness on the part of The9, who in theory could simply roll back individual servers to specific progress levels. On the other hand, players can probably get all ecstatic about getting their hands on epic gems so early (blast my slacker server!).