2.4 Patch notes are starting to come in slowly, here's a good summary from the people at MMO-Champion.

Patch Notes for the 2.2.2 Patch:

General

• Brewfest has begun and members of the Horde and Alliance can enjoy a multitude of activities, quests, items, and even Ram Racing. As Brewfest is about beer and food, revelers can sample the best beverages available in the world.
• Observed by both the Horde and the Alliance, Hallow's End is the celebration of the break between the Forsaken and the Scourge. Adventurers can speak to innkeepers to get silly masks to wear during their adventures, and much more. This is just one way to celebrate Hallow's End. New Holiday World Event: The Headless Horseman has been seen terrorizing local villages.

• Added a new graveyard to the Southern Barrens.
• Added a new graveyard to the Western Plaguelands.
• Added a new graveyard to the Alterac Mountains.
• Added a new graveyard to the Searing Gorge.
• Added a new graveyard to the Badlands.
• Added two new graveyards to Tanaris.
• Added two new graveyards to Winterspring.
• Added two new graveyards to Stonetalon.
• Added two new graveyards to Un'Goro.

Here's the latest 2.2.2 patch notes:

General

• Brewfest has begun and members of the Horde and Alliance can enjoy a multitude of activities, quests, items, and even Ram Racing. As Brewfest is about beer and food, revelers can sample the best beverages available in the world.
  
• Observed by both the Horde and the Alliance, Hallow's End is the celebration of the break between the Forsaken and the Scourge. Adventurers can speak to innkeepers to get silly masks to wear during their adventures, and much more. This is just one way to celebrate
  
  • Hallow's End New Holiday World Event: The Headless Horseman has been seen terrorizing local villages.

• Added a new graveyard to the Southern Barrens.
  
• Added a new graveyard to the Western Plaguelands.
  
• Added a new graveyard to the Alterac Mountains.
  
• Added a new graveyard to the Searing Gorge.
  
• Added a new graveyard to the Badlands.
  
• Added two new graveyards to Tanaris.
  
• Added two new graveyards to Winterspring.
  
• Added two new graveyards to Stonetalon.
  
• Added two new graveyards to Un'Goro.

As the title says...

• User Interface
  
  • The Hunter ability Kill Command no longer affects their current target.
  • Warlocks can no longer get both Fel Stamina and Sacrifice Shield using a macro.
• World Environment
  
  • If you get a positive reputation from combat you also get the corresponding opposite reputation reduction.
  • Crypt Fiends around Azeroth and at Hyjal Summit are now more totem friendly.
  • Fel Corruptors in Blade's Edge Mountain are now less potent.
• Bug Fixes
  • Fixed problem where players could be disconnected by clicking on an item link in cross-server battlegrounds.
  • Pets no longer follow enemies after being revived.

Here's the PTR 2.2 notes... which just went up and includes the Voice Chat!

General

• Voice Chat - The new Voice Chat feature is now available in game. Players will need to go into the options menu under Sound & Voice to activate it. Volume sliders are available for the microphone, speakers, and game-audio fade (which automatically lowers the game audio when a voice communication is received), as is a “push-to-talk” setting. Right-clicking on a player’s name now includes the option to mute or unmute that player. Muting another player blocks all voice chat from him or her; the ignore feature now blocks both voice chat and text chat from that player.
  
• Chat Channels- New Chat Channel controls and functionality are now available under the chat tab in the Social Window of the interface. The interface will now show the channels players are in or are available, depending on the area of the world they are in, along with new private channel controls.
  
• A new feature for reporting players as being AFK in battlegrounds by right clicking has been added. When enough reports are registered, a 30 second debuff will begin to count down. Once the timer is up a new debuff will appear that will prevent the player from gaining any honor while it is on. This debuff can be negated as soon as the player engages in combat.
  
• Resilience Rating: The reduction to the percent chance to get a critical strike now also reduces the damage dealt by damage over time effects by the same percentage.
  
• Daze: Defense skill will no longer reduce the chance players have to receive the Daze effect when attacked from behind by enemies.
  
• Corrected the damage modifier calculation for Resilience when the attacker has bonus critical strike damage.
  
• Power Regeneration: Any effect which triggers a change in your rate of power regeneration (Mana, Rage, Energy, Focus) will now cause an immediate reward of some power at the old rate of increase, and then begin new “ticks” of power at the new rate approximately 2 seconds later. This was done to improve functionality of abilities such as Evocation and Innervate so that they did not have wasted “ticks”.
  
• Mac Movie Capture: the Mac client can now capture in-game video to QuickTime movie files using a configurable choice of codec, resolution, and frame rate. Two new entries have been added to the Key Bindings dialog for start/stop recording and for cancellation of a recording. For more detailed configuration options please see the Mac Options panel in game. Mac OS X 10.4.9 and QuickTime 7.1.6 or better are required. Not all machines have enough performance to smoothly capture video at high frame rates; end user experimentation will be required to find appropriate settings for each system.
  
• Pets are now affected by Paladin greater blessings.
  
• Non-combat pets may not be selected as the target for spells or abilities.
  
• Non-combat pets now have the tag “Companion” instead of “Minion”.
  
• Being attacked by guardians, such as summoned Treants, will no longer automatically causes neutral guards to attack you.
  
• Meeting Stones can no longer be used to summon players that do not meet the level requirements.
  
• Damage and health leech effects always affect flying players even if they are immune to the rest of the spell’s affects while in flight.
  
• Dueling players may not use a Lightwell that they didn’t create themselves.

Here's some of the notes:

• The Consortium and Protectorate need your help! Players with Honored or higher reputation with the Consortium should seek out Protectorate Advisor Rahim at the Stormspire in Netherstorm or Commander Ameer at the Protectorate Watch Post in Netherstorm to get a briefing on the most recent nefarious activities of the Ethereum.
• Skettis is now available. Players will need a flying mount to reach this new area.
• Nether Drakes are now in the game and can be gained by continuing the Netherwing faction and quest line.
• Ogri'la is now available.

PTR 2.1.0 is up and here are some of the patch notes. Click the link for all of them.

General
- The Black Temple is now available for play and Illidan awaits. Are
you prepared?
- The Consortium and Protectorate need your help! Players with Honored
or higher reputation with the Consortium should seek out Protectorate
Advisor Rahim at the Stormspire in Netherstorm or Commander Ameer at
the Protectorate Watch Post in Netherstorm to get a briefing on the
most recent nefarious activities of the Ethereum.
- Skettis is now available. Players will need a flying mount to reach
this new area.
- Nether Drakes are now in the game and can be gained by continuing the
Netherwing faction and quest line.

Just in case you have seen these being sent around and think they could be legit - they're not.

General

Equivalent percentages are now displayed for combat ratings on item tooltips.
Holiday quests and other seasonal quests done during past events that previously could not be repeated can now be completed.
Weapons with uncontrollable procs (e.g. stun) will no longer trigger diminishing returns in PvP.
Repeatable quests no longer award experience to players at max level (70).
Talent bonuses are now reflected in the character tab.
Confused guards in Silvermoon City, Exodar, and other places no longer give directions to locations in Stormwind City.
System performance when enabling the full screen glow effect improved.
Players using dual video card setups will now have their graphic options optimized by default.
Guards now give directions to more locations than before (e.g. reagent vendors, faction leaders, nearest repair NPCs etc.)
Booty Bay is now flagged as outdoors.
Fixed display issues with female Blood Elf models.
The male gnome /cheer animation now plays properly.
Blood Elf and Draenei player characters are now properly flagged in many quests.