Have you heard of Minetest?
http://c55.me/minetest/It's a C++ minecraft clone that's going pretty well.
The guy who runs it, celeron55 says that making a Minecraft clone is pretty much the ultimate game programming challenge for him.
I think I'll stick to learning SDL!
Anyways, well done, this looks pretty cool.
Are you going to make it into a full minecraft clone? (When will you stop development)