Voxel Farm is coming to Unreal Engine. In fact, this is not so new (see here), but there are some news:
The last version on Voxel Studio can now build package to be used inside unreal, through a provided warper (in early stage of developpment, for evaluation purpose). Voxel Farm team is working on a true plugin.
Voxel Farm (the engine) and the IDE to edit Voxel data (Voxel Studio) can be seen as a content creator suite (like 3DS max or so) with a intimate integration in engines (like Speetree or Substance). What it brings is the voxel representation of the world with LOD and Physics, in game. That means total freedom to landscape AND building representation, including caves, overhang, etc, and with a great ease of modification (inside Voxel Studio). On the generation side of the product, the building grammar used inside voxel studio is a very powerfull approach to create procedural content (using a CGA-shape like approach). You can also have realtime modification of voxel (destruction, at least, and maybe creation).
The typical workflow would be to feed standard Heighmap (generated in WorldMachine for example) to Voxel Studio, where you carve and sclupt, add caves, building, etc, then use the Unreal package to go on with the level generation in Unreal Engine4.
I think this is a solid way of inviting Voxels to Unreal Engine !