http://store.steampowered.com/news/3408/ Updates to Left 4 Dead 2 have been released. The updates will be applied automatically when your Steam client is restarted. The major changes include:
Gameplay
* Now ghost PZ's can never be staggered
* Enabled PZ bots
* PZ bots use their more aggressive survival mode behavior in versus and scavenge
* Enabled finale manual spawn by default
* Fixed human PZ players not getting counted when they were dead, allowing extra PZ bots to spawn
* Reduced effectiveness of melee weapons against the Tank ( 5% of max health, from 10% )
* Fixed a case where a player who dies, then is rescued from a rescue closet, and then is revived from a ledge hang receives the secondary weapon that he lost when he was initially killed
* Improved SurvivorBot AI in cases where the bots refused to shoot through their teammates and became non-responsive
* Fixed issue with witch sometimes taking on uncommon common properties
* Fix for cheaters quitting before the vote to kick them would succeed and avoiding ban on server
* VAC banned users can now play L4D2 single-player, commentary mode and credits