Valve is getting ready to release a major update to its zombie co-op shooter Left 4 Dead and this week the game's official blog site posted up some details. The update, to be released automatically via Steam sometime next week, will concentrate on supporting new campaign add-ons made by third parties.

The update will include the official release of the game's SDK editing tools (the SDK has been in open beta for some time) with a few changes and fixes. The mod tools will allow players to make their own campaigns for Left 4 Dead. The update will also have some UI changes to support add-ons as will as matchmaking for any new third party campaigns.

According to the note, "Content authors will be able to package up their new maps, along with new posters, models, and textures, into a single .VPK file." They can then be placed in an addons folder in the game where they will be accessed via the game's Extras menu as seen above.