Updates to Team Fortress 2, Counter-Strike: Source, Day of Defeat: Source and Half-Life 2: Deathmatch have been released. The updates will be applied automatically when your Steam client is restarted. The major changes include:

Source Engine Changes (CS:S, DoD:S, TF2, HL2:DM)

• Updated the shared interfaces for the TF2 Free To Play update
  
• Updated the shared localization files
  

Team Fortress 2

• TF2 is now Free To Play
  
• Added the Uber Update: http://www.teamfortress.com/uberupdate/
  
• Added PL_Barnblitz, a new Payload map
  
• Added all kinds of new goodies!
  
• The Main menu now has a "Start Playing" option which presents users with various game modes to choose from. Once selected, the game matches the player into the best available server for that mode. 
  
• The Crafting interface has been redesigned to accommodate the fact that crafting blueprints are always known to players now.
  
• The Item selection screen in Loadouts has been redesigned to support selection among a larger number of items.
  
• Training improvements:
  
  • New training user interface
    
  • Added "A,W,S,D" movement instruction to Soldier training
    
  • Added ammo instruction to Engineer training
    
  • Clarified many instructional strings
    
• Added new voting sounds
  
• Fixed various Coaching bugs
  
• Fixed various gameplay bug