We've known for a while that patch 1.12 will include some PvP changes, including the addition of world PvP objectives. However, Blizzard employees have been reluctant to provide any details - until, apparently, today, when someone let IGN on a first glimpse of the world PvP system. So what should you expect? New outdoor objectives in Silithus and Eastern Plaguelands that will flag players who participate as PvP, and provide buffs to all faction members in the zone upon success. In Silithus, players will collect dust to turn in to camps of their faction (remember the camps for the "Field Duty" quests? This will be where you'll do your turnins.) - however, picking up the dust will flag players PvP.. In Eastern Plaguelands, there are several towers that will be converted into capturable PvP objectives. If your faction controls all of the towers, they'll receive zone-wide buffs.
There's still no information on the sort of rewards that one might gain from this activity, but the fact that Blizzard says "no new PvP rewards" are on the horizon makes me wonder if there's nothing more than honor at stake.