Valve have announced some more Left 4 Dead content:

Entitled "Crash Course," the latest DLC delivers new single-player, multiplayer and co-operative gameplay to both platforms. Targeted for release in September, "Crash Course" bridges the gap between the end of the "No Mercy" campaign and the beginning of "Death Toll" in the original game, expanding the game universe with new locations, new dialogue from the original cast, and an explosive finale

While containing both Survival maps and a Co-operative Campaign, the primary goal of "Crash" is to deliver a complete Versus mode experience in just 30 minutes, resulting in a streamlined version of the game's existing Versus campaigns. A recharge timer for infected teammates has also been added, and item spawn behavior has changed for more balanced gameplay.

This is definitely something I'm looking forward to! One of my big issues with Versus at the moment is it takes ages to sit down and haul through an entire campaign, so having a "lightweight" alternative for those times when you just want to have a quick bash will be awesome.

The DLC (or as we used to call it back in the day, "patch") is due for release in September and will be free on PC and cost you 560 Gamers points on Xbox Live.