Updates to Left 4 Dead have been released. The updates will be applied automatically when your Steam client is restarted. The specific changes include:
Game and client changes
* Introduced fatigue to the melee attack in versus mode. You will see a HUD display when your melee swing is cooling down
* Boomer vomit will now pass through common infected
* Addressed some surround sound detection issues
* Fixed a rare crash when exiting Left4Dead on Windows Vista
* Fixed a case where the complete all expert campaigns achievement was not being rewarded
Dedicated server changes
* Corrected an issue where Windows based dedicated were sending spurious shutdown notifications to the master causing them to delist temporarily
* Fixed dedicated servers not resetting the versus team swap correctly--you could join a dedicated server that had a previous game that was swapped and arrive on the other team than what was selected in the lobby
* Renamed the tags for sv_search_key to use "key:" in the server tags instead of "sv_search_key." This should help with issues of the 63 character limit of server tags
* Fixed an occasional server crash related to voting