Updates to Left 4 Dead have been released. The updates will be applied automatically when your Steam client is restarted. The specific changes include:
Left 4 Dead
Finding a dedicated server when starting the game from a lobby is now faster and more reliable
Versus mode is now locked to Normal difficulty
Difficulty on a server is now locked to the one set by the lobby reservation
Fixed lagouts/spikes after level transition
Fixed directory issue with spray logs in some cases
Fixed video settings not saving after closing video options dialog
Corrected a boomer suicide exploit
Several minor localization fixes
Fixed disabling cheats incorrectly resetting data