Left 4 Dead Survival Pack: April 21

Tonight, it's still April 20. But when you open up those sleepy eyes and greet April 21? Left 4 Dead's Survival Pack will be there waiting for you.

Valve announced today that the free content - which will introduce new gameplay modes and open up two campaigns for versus play - will be released on Xbox 360 at 2am Pacific Time. PC owners will have to wait until "later in the day".