After spending countless hours on playing Minecraft, I decided to move on and try creating my own version of the game. If you ask me why, I am telling you: bugs

I'm not saying I stopped playing it because of bugs: in fact, I am still enjoying it, even on multiplayer wherever possible, but seeing how sometimes the game fails (redstone logic madness!), and how much difficult is for developers to add features without breaking anything else, makes me extremely curious about exploring the coding of a similar/clone game.
Yesterday I played a bit with SFML (it's like SDL but C++ oriented) and PolyVox: they coud be perfect starting points for any similar project.
Now, for the real question: who is working to a Minecraft "clone" and is willing to make it open source? Who is interested in building a shared "general block multiplayer engine" that would adapt to several different gameplays?