They released the Survival Pack update last night
Taken from CSNation
The Survival Pack for Left 4 Dead has officially been released to all PC owners! Behold the change log as it is listed below. The update should automatically download to your Steam client.
Survival Mode
• New gameplay Mode
• 16 maps including Last Stand
• Leaderboards
• 7 new achievements
Versus Changes
• Fixed a case where versus team score would continue to be recalculated after the score panel was displayed
• Fixed an issue with recalculating the versus score health bonus for a player when they are rescued from being incapacitated
• Fixed being able to start a swing as an infected, then teleport to the survivors and have the claw swing hit a survivor
• Fixed a case where teleporting to the survivors would not reset the ability timer
• Fixed an exploit where you could load the chamber of a weapon with bullets by holding down the melee key
• Fixed a case where it was not possible to join a game while it was in a finale
• Fixed a rare case where listen servers would speed up the game over time
• Removed convars related to melee fatigue
• Fixed a case where infected players would get a respawn time on their initial spawn into a map
Server Changes
• Made ms_force_dedicated_server not require cheats
• Add a message when queuing a heartbeat
• Simplified setting of game mode.
removed convars director_no_human_zombies and director_holdout_mode
added mp_gamemode [coop,versus,survival]
General
• Added lobby join and leave messages
Happy gaming, fellow survivors!
We should all play sometime this week.