Earlier this week, Valve issued a challenge to the Left 4 Dead 2 community: if 20,000 players beat the in-development "Cold Stream" campaign by Sunday, they'd get the re-release of "Dead Air" early. That goal was met in about four hours.
That means Left 4 Dead 2 owners will get the tweaked Left 4 Dead campaign early. No later than July 22, Valve says—barring an outbreak of Valve Time, naturally. The developer says its testing and finalizing the "Dead Air" re-release, as it's not yet ready for prime time.
Also interesting is that the Left 4 Dead team says it's "working on and testing a new version of the 'Dark Carnival' finale and some gameplay changes for finales in general." Dark Carnival clearly has its own final quirks, but I'm interested to see what Valve has planned for other finale changes.