I bought it a few weeks ago but only played twice (no time). My first time playing the demo I immediately was struck by several opportunities

1) converting 2D images into 3D minecraft world for artists and lazy people

2) Connecting 26 adjacent worlds to have a fluid adaptive minecraft universe. As users move from one world to the next it pulls in the data from the next set of adjacent worlds (no crossing lag). Folks can host their own worlds and pay for virtual real estate (hosting) or lay claim to a parts of a big cube, Thematically clustered worlds would be fantastic (hell worlds, water worlds, sky citiies, shopping districts, space worlds.. etc).

There's something oddly beautiful about building your own game world.