Ragefire Chasm, the low-level instance beneath the Horde capital of Orgrimmar, has undergone sweeping changes in the Mists of Pandaria beta. New quest NPCs, a new story, new enemies, and interesting clues to the grand finale of Mists of Pandaria's campaign are all buried beneath one faction's very own feet. It could be that these new objectives in Ragefire point to Garrosh's fall from ... I guess I'd use the word grace here, but ... you know ...
Four new bosses now reside in Ragefire Chasm, including:
Adarogg, a nasty flamehound that has eaten his captors
Dark Shaman Koranthal, who is performing a creepy ritual
Slagmaw, who is Magmaw, but not; name potentially not final
Lava Guard Gordoth, a caged experiment that breaks out just as you arrive