Classes

Death Knights

Applicable death knight abilities are now using the correct amount of resources (and putting them on cooldown) when there are 4 Death Runes available and the Unholy Runes are depleted.

Druids

Druids that shapeshift will now clear the Potion of Illusion buff.

Mages

Combustion damage from Ignite is no longer penalized by Resilience more than once, nor can it gain double benefit from Flashburn (mastery).

Dungeons & Raids

Dungeon Finder

If a player is kicked by vote from a dungeon finder group, the leader of the group is no longer able to invite that player back.

Firelands

Rogue Smoke Bombs cannot prevent the spawning of Magma Traps during the fight against Ragnaros.

Several creatures in the Firelands are no longer susceptible to snares or other immobilizing effects.

Unbound Pyrelords, Unbound Smoldering Elementals, Unbound Blazing Elementals, and Patriarch Fire Turtles now drop silver instead of gold.

Guilds

The Recently Mass Resurrected debuff is correctly being applied to players who are in the process of logging out of the game.

Items

Brawler’s Trophy and Core of Ripeness cannot be active at the same time as each other, or other burst trinkets.

Eternal Embers are now epic quality.

Heirloom items can once again be linked in chat.

Creating a macro to use the Runestaff of Nordrassil multiple times will only trigger the use once.

Quests & Creatures

Hyjal Regrowth & Molten Front

The Burning Treants summoned by the Druid of the Flame now disappear when the summoner is captured.

3 different elementals spawn on any given day for the Death From Above achievement, up from 1.

source

Classes

Death Knights

Applicable death knight abilities are now using the correct amount of resources (and putting them on cooldown) when there are 4 Death Runes available and the Unholy Runes are depleted.

Druids

Druids that shapeshift will now clear the Potion of Illusion buff.

Mages

Combustion damage from Ignite is no longer penalized by Resilience more than once, nor can it gain double benefit from Flashburn (mastery).

Dungeons & Raids

Dungeon Finder

If a player is kicked by vote from a dungeon finder group, the leader of the group is no longer able to invite that player back.

Firelands

Rogue Smoke Bombs cannot prevent the spawning of Magma Traps during the fight against Ragnaros.

Several creatures in the Firelands are no longer susceptible to snares or other immobilizing effects.

Unbound Pyrelords, Unbound Smoldering Elementals, Unbound Blazing Elementals, and Patriarch Fire Turtles now drop silver instead of gold.

Guilds

The Recently Mass Resurrected debuff is correctly being applied to players who are in the process of logging out of the game.

Items

Brawler’s Trophy and Core of Ripeness cannot be active at the same time as each other, or other burst trinkets.

Eternal Embers are now epic quality.

Heirloom items can once again be linked in chat.

Creating a macro to use the Runestaff of Nordrassil multiple times will only trigger the use once.

Quests & Creatures

Hyjal Regrowth & Molten Front

The Burning Treants summoned by the Druid of the Flame now disappear when the summoner is captured.

3 different elementals spawn on any given day for the Death From Above achievement, up from 1.

source