A few more undocumented changes ...
A few more undocumented changes from our users, if you spot any please report them in comments.

Raids & Dungeons

• It seems that the gold dropped by bosses in Zul'gurub and Ahn'qiraj (20 Players) has been reduced by 50%.
• Grobbulus clouds are smaller and do less damage.

Achievements

• Gotta Go! - The actual time to complete this achievement has been changed from 2 minutes to 4 minutes as of patch 3.0.8. There is currently a bug though and the text in the achievement window still shows 2 minutes. This will be corrected in a future patch. (Source)
• You Don't Have An Eternity - Both normal and heroic version of the achievement have been changed to 6 minutes. (Up from 5) The encounter has been changed and made slightly harder, the achievement isn't necessarily easier to obtain.