No, I'm not working on yet another Infiniminer/Minecraft clone. I haven't even played either game. However, I've been seeing a few posts lately about generating Minecraftian type levels, and it seems like the blocky, voxel-based worlds of this kind of game is ideal for experimenting with procedural generation of worlds using fractal methods of all sorts, so I've kinda started playing around with voxel landscapes using the PolyVox library for mesh extraction from a voxel field. I must admit, the flexibility and fluidity allowed by a voxel engine is certainly a powerful draw.
Above is the simplest of landscape functions based on a ridged fractal perturbing a membrane-like ground surface. Even with the most simple of fractals, one can create some pretty neat landscapes. I'll most likely play with it more in the future.