A new update is now automatically available for Team Fortress 2 (and Day of Defeat: Source), as outlined in this Steam News Story. The complete change log follows.

Engine

• Enabled Steam Cloud support for key bindings and custom spraypaint images
  • Added Options->Multiplayer->Advanced option to toggle off/on: default is on

Team Fortress 2

• Added new Highlander mode
  • 9 players allowed per team
  • Restricts each team to 1 of each class
  • Use mp_highlander (0/1) to toggle off/on: default is 0
• Added "bots" to the server's sv_tags convar if the server is running bots
• Fixed a weapon name localization issue
• Fixed the "tf_teamtalk" server convar not controlling text chat between living/dead teammates
• Updated the map CTF_DoubleCross
  • Fixed the map not ending correctly when using mp_timelimit
  • Changed to prevent Engineers from building on top of the shack in each base
• Updated the map Arena_WatchTower
  • Fixed a case where players could open and get stuck on the starting gates before the round start
  • Improved clipping to prevent people from getting out of the map
  • Optimized the map for better performance