It's true here is the E3 trailer
Update: IGN has a preview with more details. Highlights below:
* Survivors: Nick, Ellis, Rochelle, and the Coach
* Missions played in full daylight
* Witch behaves differently during the day – wanders around like an old homeless woman
* New weapons: silenced SMG (silencer has no gameplay implications)
* One new gameplay mode not revealed at this time
* Stronger narrative thread to connect the campaigns
* Savannah campaign where “the zombie infection hasn’t hit yet”
* Instead of a Last Stand-type finale, survivors may have to fight through a hazard-filled highway
* Director can change the layout of the map
* New boss infected: The Charger
Also
http://store.steampowered.com/news/2552/