The unnamed MMO is going to be console-only and will take place in today's world following a zombie apocalypse. Strain promises that the world will be dynamic and malleable -- think "sandbox" -- as players will build up defenses to protect settlements, lay down traps for the zombie horde and eventually take the fight to the undead. There may also be gardening (yup, you read that right).
A more dynamic world isn't the only cue from modern MMO development that Undead Labs is taking -- the game will skew more toward quick action-based fights than traditional MMO combat: "Banish the memories you have of the PC MMO paradigm for combat, and start thinking AAA console action game... weapons (like the M14 assault rifle or long-bladed machete) need to feel snap-fast and satisfying, to pierce bones and dismember limbs just so."
While the title is still in very early stages, EGM says that the team is looking to allow a more free-form character development, with players taking on specialty roles instead of being forced into rigid class constructs. You can read the full analysis over at Game By Night.