Want to kill zombies this summer? Well, you can't. You'll have to wait until November, according to Shacknews. Yes, Left 4 Dead has been delayed by a couple of months (well, from what was always a fairly inspecific late Summer/Autumn date, so one could argue it isn't a delay at all). Balls.
Quality control and making the game "approachable to players of all skills" are the cited reasons that the game can't be released now, despite apparently being fully playable. Post-TF2 and with developer Turtle Rock now owned by Valve, I guess the pressure to deliver is fairly intense. So I rescind my "balls" - because I'd much rather wait than have the game disappoint. More positively, there will be a L4D demo, though probably not until after release.