A Blizzard rep posted in the forums:
These items are obtained by defeating Protector Kaolan last on the Protectors of the Endless encounter.
The Protectors of the Endless encounter is the first encounter in the Terrace of Endless Spring raid. It consists of three "Protectors" - Protector Kaolan, Elder Regail and Elder Asani.
When one of the three dies, each remaining Protector heals fully, gets a damage increase of 25%, and access to additional abilities. Protector Kaolan has the hardest additional abilities, so will usually be targeted and killed first.
MMO Champion has more information on the encounter here, including a explanatory video of the encounter from raid testing and a loot table.
The raid itself will be opened on October 30 (November 6 for LFR), and will only be accessible to those who have already cleared the Heart of Fear raid.