Plants vs. Zombies GOTY Edition - Valve
Updates to Plants vs Zombies: Game of the Year Edition have been released. The updates will be applied automatically when your Steam client is restarted. The major changes include:

Updates:
  • PC/MAC
    • Updated achievement descriptions
Fixes:
  • MAC
    • Fixed crash on accessing Crazy Dave’s Store.
    • Fixed crash with resuming adventure mode after exiting game on non-gameplay parts of a level.
Oddworld: Munch's Oddysee - Valve
Updates to Oddworld: Munch's Oddysee have been released. The updates will be applied automatically when your Steam client is restarted. The major changes include:
  • Resolved crashing issue in Raisins Cave at the start of the game.
Pirates Vikings & Knights II - Valve
Updates to Pirates, Vikings, and Knights II have been released. The updates will be applied automatically when your Steam client is restarted. The major changes include:

New game Mode: Trinket Wars
  • Replaces Holy Grail game mode. Each team has their own trinket carrier whom they must defend while killing the other teams' players.
  • tw_saints is now in rotation and runs the Trinket Wars game mode.
New Achievements and Titles:
  • 15 new achievements including: Sword At A Gunfight, Traveler, Some Friend You Are, Black Powder Finish, Hollywood Physics, Meat Carver, Final Strike, In Good Company, Superior Messiah, Mine's Better, The Chosen One, Sharing Is Caring, I Be Unstoppable, So Come Take A Drink..., One Man Army
  • Many achievements now unlock Player Titles which can be selected from a new 'Character Info' screen in the main menu. Titles appear next to the player's name in the MVP screen and when mousing over their model in-game. Example titles include: the Messiah, the Invincible, the Parrot Slayer and many more!
New Sounds and Voice Menus
  • Many new sounds for weapons and general map ambiance.
  • New voice menus that include dynamic objective commands and other helpful dialogue.
  • Unique voices for each class.
King's Bounty: Crossworlds - Valve
Updates to King's Bounty: Crossworlds have been released. The updates will be applied automatically when your Steam client is restarted. The major changes include:

Updates

  • Repairs a failure, which appears while checking the skills of the Rune Mage.

  • Orcs on the March
    • Crash fixed at Assassin's Know Weakness skill.
    • Error fixed at orc shaman's Adrenaline Maximum.
    • Error fixed at spells Poisonous Spit, Black Hole and Soul Draining at the boss arenas.
    • Error fixed at Skeletons' skill Bone Gate at the Arena of Chaos.
    • Description of skills fixed at Rune Mage, Faun and Bone Dragon.
    • Feature Recruiter fixed.
    • A dialogue of Rock Porter fixed, if you don't take quests for spy searching.

  • Defender of the Crown
    • Failure fixed after the defeat in the battle for medals (after the talk with smuggler Hogben).
    • Ancient Ent's skill Summon Swarm doesn't recharge the skill Running now.
Balance Changes
  • Orcs on the March
    • Abilities of the Infernal Dragon were strengthened.
    • The following creatures were strengthened: White Kraken, Fauns, Rune Mages, Goblins, Orc-leaders and Tirexes.
    • Orc-shamans were weakened.
    • The feature Favorite Enemy of humans gets updated in every new battle.
    • The AI of Alchemist and Engineers was updated.

  • Defender of the Crown
    • The enemy hero Mahruk was strengthened.
Additions and upgrades:
  • Orcs on the March
    • Detailed information on the trophies in the Military Academy added; (c) ilih.
    • A specified log during the receipt of Adrenaline by orcs added.
General
  • Support of 16:9 format added.
  • New opportunities for game modders added.
Team Fortress 2 - Valve
Updates to Team Fortress 2 have been released. The updates will be applied automatically when your Steam client is restarted. The major changes include:

Team Fortress 2
  • The Blighted Beak is now a misc slot item.
  • The Buffalo Steak Sandvich's speed boost no longer stacks with other speed boosts.
  • The Rocket Jumper and Sticky Jumper now have no max health penalty, and have damage vulnerabilities instead.
  • Duel fixes:
    • Duels can no longer be initiated when the round is not fully running.
    • If you challenge someone that has already challenged you, the duel is automatically accepted.
    • Fixed an issue where a dueling mini-game item was marked in-use even though the duel was rejected.
    • Duels are now refunded if a server plugin forces a participant to switch teams.
  • Loading screen:
    • Only shows the duel leaderboard if you've been dueling, or if your friends have been dueling.
    • Shows your personal stats whenever it's not showing the duel leaderboard.
  • Custom hitsounds:
    • Must now be specified by replacing the 'tf/sound/ui/hitsound.wav' file.
    • Can now be used under sv_pure 1/2.
  • Improved performance on Degroot Keep.
  • The "Fabricate Class Headgear" recipe no longer has a chance of creating all-class hats.
  • Fixed spectator mode sometimes ending up in a state where you were half-embedded in your spectator target.
  • Fixed a bug in the Kritzkrieg’s animations.
  • Fixed round restarts not cleaning up weapons correctly for a frame (fixes a variety of weapon attribute issues, such as players having less health or less ammo than they should)
  • Fixed painting issues in several of the Australian Christmas hats.
  • The Sniper scope is now visible when viewing First Person Spectator mode on a zoomed Sniper.
  • Medieval Mode's auto-roleplay now ignores text beginning with '!' or '/' (so SourceMod commands aren't modified)
Super Meat Boy - Valve
Christmas Present for You

World of Goo ball now playable, type ballgoo at the character selection screen

Christmas Present for Me

Now when your game crashes, it makes a mini-dump and sends it to me.
Alternativa - Valve
Updates to AlternativA have been released. The updates will be applied automatically when your Steam client is restarted:

- fixed: freezed control cursor
- fixed: non-responding PDA issue
- fixed: several other issues

Arma 2: Private Military Company - Valve
Four brand new scenario missions for owners of A2:PMC.
One showcase and three distinctive single-player missions add extra weight to PMC's substantial co-op campaign playable content:

Infiltration - Sneak under the cover of darkness to destroy a rocket artillery test site.
Reaction - Battle through the mist to recover missing clients.
Provision - Take to the air to deliver a crucial cargo drop for UN troops in central Takistan.
Showcase - Enjoy the diversity of the PMC faction in a showcase mission.


ARMA 2 : Private Military Company version 1.00-1.01 changelog
-------------------------------------------------------------

VERSION 1.01 HIGHLIGHTS
-----------------------

* 4 new bonus scenarios for owners of the full version of Arma 2: Private Military Company


PMC Data
--------

* Changed: GPS added for all SUVs.
* Fixed: Shadow artifact on bridge on Proving Grounds map.
* Changed: XM8 optics reworked.
* Fixed: XM8 Front grip
* New: Ammo crate with PMC weapons.

PMC Missions
------------

* Added: Campaign teaser including CP00 and trailer.
* Fixed: CP10A - The Boss was not leaving the villa when in danger.
* Fixed: CP10A - Player was not able to finish the Boss from distance.
* Fixed: CP08B - Group callsign was "Sword", not "Spear".
* Fixed: CP08A - Player was not able to access helicopter gear menu.
* Fixed: CP07 - Client UAV reenabled again.
* Fixed: CP05 - Mission did end before conversation was finished.
* Fixed: CP02 - Dixon fired only once, causing mission not to continue.
* Fixed: CP00 - Mortar explosions now occur further away from player.
* Fixed: Backpack content is now saved between CP05 and CP06.

Arma 2: Operation Arrowhead - Valve
ARMA 2: Operation Arrowhead version 1.56-1.57 Changelog
------------------------------------------------------

VERSION 1.57 HIGHLIGHTS
-----------------------

* improved netcode (better locality handling)
* new scripting commands


Engine
------
* Fixed: Cursor on the windows borders no longer flashing when attempting to drag/resize the window.
* Fixed: Win7/Vista Aero preview should no longer be activated by mouse movement while playing.
* Fixed: Helicopters no longer lifting off when aircraft passed over them (http://dev-heaven.net/issues/14589).
* Fixed: AI Helicopters wobbling up and down (http://dev-heaven.net/issues/14410).
* Improved: Enemy targets are now unassigned once their crew is killed.
* Fixed: doFire did not work on most targets.
* New: Multihome servers support. Commandline parameter -ip=my.ip.add.res available.
* Fixed: SetCaptive doesn't stop AI shooting at a unit/player (fix 2.0)
* Fixed: Groups were missing units after group changes on JIP clients.
* Fixed: LOD switching with -exThreads=0
* Fixed: Despite irTarget = 0 units/objects could be locked with TAB.
* Fixed: SetCaptive doesn't stop AI shooting at a unit/player.
* New: allMissionObjects script command.
* New: Script command setPlayerRespawnTime.
* New: new AllDead command.
* Fixed: Video playback stuttering.
* Fixed: Locality issues of objects in MP (mainly updates from nonowner errors). Version raised to 1.57 due to MP incompatibility.

Data
----
* Add: camo (replaceable textures) selections for M2A2/3.
* Changed: GPS added for all SUVs.
* Fixed: A/MH6 main rotor artifact.
* Fixed: Missions: 06 From Hell, task "Locate the pilot" always failed.



Worms Reloaded - Valve
Updates to Worms Reloaded have been released. The updates will be applied automatically when your Steam client is restarted:

“Following hot on the heels of the Team Fortress pack, we now have the Community pack which contains missions, maps, hats and gravestones all inspired by and designed by the Worms community. The designs were chosen from a number of competitions run earlier on in the year and finally they are ready.

The community pack contains: -
  • 5 Single Player Missions
  • 3 New Multiplayer Maps
  • 3 New Hats
  • 3 New Gravestones
We've also fixed a bug that caused unlocked items to be no longer available.

We'd like to take this opportunity to thank all our Worms fans for their help in making Worms Reloaded such a success and wish everyone a Merry Christmas and a Happy New Year.”
...