After coming out of a random BG, I started hearing different music in Orgrimmar after patch 5.2.
After a little bit of searching through the game files, I found it.
Personally, I like this a lot more than the older Org music.
Here is the macro to play it in game.
/script PlayMusic("Sound\\Music\\Pandaria\\MUS_51_GarroshTheme_A_Hero_01.mp3")
Based on the name, I have to guess that this is Garrosh's theme or something.
Also, found a few Alliance ones too. This one is my favorite of them.
/script PlayMusic("Sound\\Music\\Pandaria\\MUS_51_AllianceBattleMarch_01.mp3")