It does feel like shards because of the gates and the relative similarity between galaxies but the fact is that if every inhabitant of the game were to move towards the center they would all eventually converge (assuming the system handled it,) something not possible in true shards.
The game engine still fails if to many people gather in the same area. The game design and zone limts artifically avoid this, but it has nothing to do with stackless python.
What I should have said is each zone runs on a seperate physical server (or part of one) and their innovation is to build a game that let's move across HW systms with little issue.
Note: They use a shared database for some game states, but they don't let any CPU read memory from any other CPU directly. It's a question of system archtecture not language features.
