An update has been released for Left 4 Dead 2.

- Quick Match option for all modes allows players to prefer "Official Servers Only" or "Any Servers"
- Added localized UI and subtitles for Vietnamese
- Increased string commands per second limit to fix some false disconnects
- Prevent manually initiating some talker responses that trigger longer conversations
- Fixed color correction for some maps where it was missing or incorrect
- Fixed melee animation while carrying a fireworks crate
- Fixed M60 not using the correct walk calm animation
- MP5 changed to the slightly better rifle reload animation
- SG552 changed to use assault rifle animations and military sniper zoom animations
- Fixed incorrect sound cue for player infected when a survivor dies
- Changed some mob onslaughts to classic panic events in the L4D mutation
- Boomer bile slows tanks in Tank Run mutation
- Several Rocket Dude mutation fixes and performance improvements
- New survivor alert response rules for intense combat situations
- Scripting:
• Fire the "KilledZombie" response concept when killing a Witch.
• New "EntityOutputs" class containing functions to manipulate entity output connections.
? GetNumElements, GetOutputTable, HasOutput, HasAction, AddOutput, RemoveOutput
• Expanded response rules testbed.

More...