[Oops, gmail interrupted my draft]

The code is on github:

https://github.com/idryanov/2schematic

It supports several different coloring models, and simple color
filter. The output is .schematic files, which you can then view or
edit inside mcedit, and export to Minecraft worlds.

I hope you enjoy our contribution!

Cheers,

Ivan

PS. I saw yesterday that Jon Stephan independently released a very
similar package. Great work - I look forward to checking it out! The
3D mapping research appears to be converging to its inevitable
conclusion...