This looks like it's the Shado-pan Monastery in Kun-Lai Summit. (Thanks to a couple people for pointing this out.) It serves as the training grounds for the Dragonborn Shado-pan Clan, a group of pandaren ninjas who are tasked with protecting Pandaria. In the dungeon, the Sha are invading, and you have to deal with it.
Some people have noted that a small version of this image appeared in a Ghostcrawler postmortem, but we haven't seen a large version yet.
The dungeon preview video and more information about Kun-Lai Summit, after the break.
Blizzard -- Kun-Lai Summit
High atop the frigid northern peaks of the Kun-Lai Summit looms the Temple of the Tiger, an ancient training ground protected by an elite force of martial priests, along with the spirit of the White Tiger itself. Deeper into the mountains is the hideout of the Shado-pan: a mysterious order charged with protecting Pandaria from the dark things buried beneath its surface. When the isolated people of Kun-Lai are threatened by marauders from the west and a Zandalari troll menace invading its northern shores, they turn to the Alliance and Horde for help.