Undead Labs has taken the time to answers questions from fans that stemmed from a recent article discussing the world of Class3, their upcoming zombie survival game for Xbox LIVE Arcade that will be followed by the Class4 MMO. While the Q&A doesn't provide many concrete answers, it's an interesting look at their take on the genre.
For example, you'll be able to use a vehicle to increase your storage capacity, but they include the disadvantages of "sound, visibility, fuel and maintenance." There won't be weather or seasons in Class3, but they'll play a factor in the Class4 MMO. There will be water in the game, and you will be able to swim. Diseases will be among the many hazards you'll face.
If you're at all interested in Undead Labs' zombie franchise, this Q&A is worth a look.