The demo itself will contain a section of the "Parish" (the 5th of 5 campaigns apparently) which can be played by up to 4 players at once (with 2 player split screen on the 360 demo). Enough to give you a sense of the new weapons and infected in the game. But when will you get to play the demo? That's where things get complicated.
If you pre-ordered the game - on either the Xbox 360 or Steam - you'll be able to play the demo starting on October 27.
If you play on the PC, or have a Gold subscription to Xbox Live, you'll get the demo on November 3.
Silver members of XBL will finally get the demo a week later on November 10.
Left 4 Dead 2, the sequel to the best-selling and critically-acclaimed co-operative multiplayer thriller, promises to set a new benchmark for co-operative action games and become one of 2009's marquee titles. Set for release on November 17, the title adds melee combat to enable deeper co-operative gameplay, with items such as a chainsaw, frying pan, axe, baseball bat, and more. Featuring new Survivors, boss zombies, weapons, and items, Left 4 Dead 2 offers a much larger game than the original with more co-operative campaigns, more Versus campaigns, and maps for Survival mode available at launch. Left 4 Dead 2 is targeted for release on Xbox 360 and the PC on November 17, 2009.