Warriors will dress themselves in the Molten Giant Battleplate, made in the image of the new molten giant model. You may remember molten giants and molten destroyers from the Molten Core. They also wander fields of lava in the Firelands, ready to lumber over to unsuspecting players.
Druids will be donning the Obsidian Arborweave sets, based on what appears to be the tree that Malfurion and the Avengers of Hyjal are growing in the Firelands as the foward base against Ragnaros. Maybe, as a restoration druid, you were upset that Tree of Life was not a permanent form anymore. Well, now you get to dress up like a tree. Compromise. Hit the jump for a pic of the druid set.
By the way, Obsidian Arborweave is the most "Blizzard" name for anything I have ever seen. I hope that guy got a raise.