This new season will be 13 episodes long, and starts right off where last season's finale ended, with the survivors escaping the Atlanta Center for Disease Control right before it exploded. As they leave the city limits, they'll wander into Hershel's farm, a location also featured in the comic book series, and where much of the episodes will take place.
The Walking Dead Season 2 cast, or what's left of them
The Walking Dead's second season will be split into two arcs: the first seven episodes comprise the first arc, then the series will go on hiatus and return for the second arc on February 2012. I hope the wait between arcs won't be that long, though.