Blizzard recently released Hotfixes to the 4.3 Patch.
Notably, Zul’Aman & Zul’Gurub received nerfs.
Hunters and Paladins received minor bug fixes.
A number of Dragonsoul Bosses received bug fixes.
Yor’sahj received a nerf to damage in 25-player mode, as he was believed to be overtuned/too difficult in comparison to
his 10-player version.
Click this link for all the details on the Patch 4.3 Hotfixes as of Dec 20, 2011.