The Repopulation is a sense of a world in motion, shaped by players but also influencing player actions. August's updates to the game included the implementation of the Area and World Event systems, facilitating just that sort of gameplay. According to the most recent development blog, these systems track what's going on in the world, direct players to unexpected happenings, and then start to chain new events based off of those metrics. There are also NPCs in place to direct players toward hotbeds of activity.
The game's other mechanics have also received further tuning. Cities can now benefit from new happiness-increasing structures and more flexible placement options, combat values have been tweaked, and new engagements have been added for siege warfare. There is also a variety of bugfixes and general balance tweaks, which can be found in the full patch notes included with the development blog.