You'll be pleased to know that on top of the server-side patch, Valve has just released
a title update for Left 4 Dead
that's a client-side patch for stopping hackers and exploiters
. You know, because nobody likes dealing with a dozen witches while in a safe room. Safe rooms are meant to be safe. Valve confirmed with Joystiq that patch not only fixes all the cheats from working online, but also prevents the L4D
shenanigans from working on system link.