Patch 4.0.6 (undocumented changes)

Achievements

 * and have been removed as criteria for  and  respectively, making it possible to complete the latter two again.
 * The guild achievement Everyone Needs A Logo is fixed.
 * The Bounce achievement is now possible for those who previously could not complete it due to phasing issues.
 * Certain achievements that previously did not show progress, such as Rock Lover, The Glop Family Line, and Tol Barad Veteran now display progress.
 * The title The Exalted is now awarded for earning exalted reputation with 50 factions, up from 45. The title has been removed from players who had it previously if they do not currently have 50 exalted factions. This has been reversed on February 14, 2011. The achievement tooltip still states otherwise.
 * Critter Kill Squad has been fixed to only grant 1 kill per party/raid per critter, as opposed to 1 kill per party/raid member per critter.

Hunter

 * Only one target can be affected by Freezing Trap at a time
 * Steady Shot and Cobra Shot no longer cause the hunter to rotate to face the target. An error is still displayed if the target is behind the hunter.

Shaman

 * The healing spells Healing Wave, Healing Surge, and Greater Healing Wave now have new water-based animations.
 * Casting Fire Elemental Totem and Earth Elemental Totem no longer causes a shared 2 min cooldown. They can now both be used at the same time.

Warlock

 * Devour Magic (felhunter) Cooldown increased to 15 seconds, up from 8, but down from 20 the patch notes indicate.

Warrior

 * Inner Rage (warrior ability) Cooldown is 30 seconds, in contradiction to the patch notes.

Priest

 * Dispersion Casting while mounted will no longer dismount you.
 * Levitate It's no longer possible to "glide" along walls, without losing altitude.

Dungeons & Raids

 * The Dungeon Finder no longer states whether an instance is in progress.
 * The Raid Browser again properly displays available raids.

Bastion of Twilight

 * A Summoning Stone has been added outside the entrance.

Deadmines

 * Vanessa VanCleef
 * Although the third set of ropes has been removed, she still triggers an explosion as she dies. Move away from her to avoid death.

Halls of Origination

 * Temple Fireshapers now consume (and consequently can run out of) mana casting Molten Barrier.

Lost City of the Tol'vir

 * Players can no longer climb on Lockmaw's statues.
 * Siamat
 * The Minions of Siamat are no longer stationary.

Shadowfang Keep

 * Commander Springvale
 * He now develops Separation Anxiety and increases damage by 200% if taken out of his room.
 * It is no longer possible to despawn his initial adds by aggroing them and immediately resetting the encounter (eg. through Feign Death).
 * A few trash mobs have been removed.

Stonecore

 * If the second or third groups of trash mobs before Corborus are engaged, the first one will also engage if still alive.
 * A pack of trash before Ozruk (to his right) has been removed.

Vortex Pinnacle

 * Asaad now drops Thundercall in both normal and Heroic flavors.

Items

 * The Abyssal Seahorse mount may now be used while a player is standing on the sea floor in Vashj'ir.
 * Argent tournament banners now all show the correct model again when used.
 * Captured Lightning has a new icon.
 * Conch of Thundering Waves has a new icon.
 * The buff from Faded Wizard Hat now disappears when removing the hat.
 * Mandala of Stirring Patterns will now proc off of HoT casts.
 * Rogue's Draught has a new icon.
 * The model for Cookie's Tenderizer has become less funny and more menacing.
 * Some old-world Relics are no longer class-specific.
 * Several relics had their icon changed.
 * Druid Tier 11 Stormrider leg pieces changed from a tunic graphic (skirt) to leggings (pants).
 * Elementium Lockbox has been added to the game.
 * Looting Currency from bags now shows the amount of currency after the name when getting just one.

Professions
All Profession Cooldowns with a 24 hour cooldown now state 'Cooldown resets at midnight' as opposed to a countdown.

Alchemy

 * Transmute: Living Elements has changed for those who are a Transmutation Master. Instead of usually get no procs and sometimes getting a big proc of 14-16 of a random volatile, now you will always get a smaller number (4-8?) of an extra volatile.
 * Transmute: Pyrium Bar now only requires one Elementium Bar, one Volatile Earth, and produces 3 Pyrium Bar.
 * Flask of Enhancement now lasts 2 hours, and can be refreshed without cancelling the buff first.

Archaeology

 * Survey cooldown reduced to 3 seconds, down from 5.
 * You can now solve projects while mounted.
 * Seven new Tol'Vir Dig Sites in Uldum added: Akhenet Fields, Obelisk of the Stars, Sakhet Wastes, Schnottz's Landing, Neferset City, Cursed Landing and Lost City of the Tol'vir.
 * Four new Nerubian Dig Sites: Plaguewood, Terrorweb Tunnel, Pit of Fiends, Sands of Nasam
 * It is now possible to walk through all unearthed archaeology finds.
 * On the Current Artifacts page, a fragment counter under each racial project currently worked on lists available fragments compared to fragments required. The race icons will also pulse as a visual cue when a current project can be solved.
 * The progression bar for research projects appears to have been accidently shifted to the left. Having all the fragments needed will not fill the progression bar.

Cooking

 * Recipe: Feathered Lure has been re-added to the appropriate recipe vendors in Stormwind and Orgrimmar.
 * Recipe: Scalding Murglesnout has been added.
 * Fresh Water has been removed from all cooking recipes, or replaced with Refreshing Spring Water.

Enchanting

 * items of iLevel 316+ now only require a skill of 450 to disenchant, down from 500.

Engineering

 * Big Daddy can now be learned from trainers.

Fishing

 * A new mouse cursor has been added, in the shape of a fishing hook.
 * About two extra seconds of leeway added before the channel of fishing expires.

Herbalism

 * Herbs respawn much more quickly. This is especially noticeable with Whiptail in Uldum.

User Interface

 * The three statuses (Red, Yellow, Green) are shown in the taskbar button of Windows 7 and Windows Vista if the content is not fully downloaded.
 * Mousing over the Game Menu icon now provides two latency numbers; a home and a world.
 * The Auction House offers to filter for items of quality.
 * The search filters for ammunition and soul bags have been removed from the Auction House.
 * Having "Consolidate Buffs" disabled under the Buffs and Debuffs section of the User Interface menu now works as intended. Prior to this patch, it would automatically re-enable upon log out even if the box was unchecked.

Quests

 * The Lovely Charm Bracelet quests for Thunder Bluff and Ironforge are fixed for the new city bosses.
 * Credit for killing Tank for Shark Tank no longer requires being in a group that tagged it.
 * The mobs for the level 81-85 version of the daily Crushing the Crown drop level loot equal to their Northrend counterparts only.
 * Troggs which drop Bag of Verlok Miracle-Grow for Through Persistence now drop Sprinkle of Verlok Miracle-Grow if they don't drop the bag anyway. 5 of these sprinkes can be combined to form a full bag.

World

 * You can now mount and fly within the Temple of Earth in Deepholm.
 * The mailbox at Ramkahen now has a new model, and two additional ones have been added in close vicinity.
 * Mounting and dismounting seems to have a new animation and sparkle effect
 * Mounts are now usable in the Stormwind Gryphon Roost (flight master area).
 * Mounts can now fly through the Gryphon pipes in Ironforge.
 * Northrend Argent Tournament jousting shield icons around the character now properly update.
 * You are no longer dismounted or removed from Flight or Travel Form when entering Vir'naal Dam.
 * Exodar quartermaster has been moved from the old flight-path location to the new location.
 * Chairs beside the Justice and Valor points vendors in Stormwind have been replaced with weapons racks.
 * A Hero's Call Board and Warchief's Command Board are now present in Dalaran in their respective faction areas.
 * Ghastly Scavengers on Tol Barad Peninsula are now neutral to players.
 * The foxes of Tol Barad Peninsula are now skinnable.
 * Horde porting into Deepholm now arrive in front of the Orgrimmar portal instead of the Stormwind portal.
 * The exit from the Deeprun Tram to Stormwind has been updated past the portal to include the change in tunnel level.
 * There are now mobs located at the Obelisk of the Moon after its final questing phase.
 * Dalaran will get even more empty, as Larisse Pembraux in Stormwind now sells heirlooms for Justice Points.
 * Retrieved fresh from the Stagecoach Crash Site, Stormglen Village in Gilneas now has an anvil and forge!
 * Vendetta Point in Southern Barrens now has a flight master (Horde)
 * Guards have been added to many towns throughout the world.

Companions

 * Moonkin Hatchling now flies with your flying mount.
 * The Smolderweb Carrier and Worg Carrier have been returned to the game as 100% drops, from Mother Smolderweb and Quartermaster Zigris respectively.

Bug Fixes

 * Female worgen now use the correct sound effect when laughing.
 * Elementium Stormshield now properly displays on players that have it equipped.
 * The attach point of Wild Hammer has been fixed, so you grip it by the hilt, rather than the top of the shaft.
 * Capital city tabards now work properly in Wrath of the Lich King dungeons. They have the same reputation rewards for killing trash mobs and bosses (15 and 300 respectively) as in Classic and Cataclysm dungeons.
 * Various mounts now again make sounds when moving. Examples include X-53 Touring Rocket and Turbo-Charged Flying Machine.
 * Bind to Account items from Cataclysm factions, such as the Earthen Ring, no longer require achieving the same reputation level to use as they do to purchase. Items purchased before the patch still require the same reputation to use.
 * Phasing of Render's Crater in Redridge Mountains after the quest Detonation has been vastly improved, with mobs no longer constantly falling from the original phase of Render's Valley. Flying in and near the eastern half of the zone also no longer produces a flight ceiling effect.
 * The flight master icon mistakenly placed at Keeshan's Post in Redridge Mountains has been removed.
 * Players can now visibly emote while walking again!
 * /mountspecial noises and animations can no longer be spammed via animation cancel.