Well, the C version of kpkg is now hosted at: http://code.google.com/p/kpkg. It would be cool if people start checking it out.
Upgrade support is working partially, as only one package at the time can be upgrated, I will try to finish the whole upgrade support soon.
If any people want to use kpkg in their personal distributions (I don't think ubuntu/suse/etc... users will want to run kpkg on their systems, but who knows), it would be nice to know.
Also patches to add more functionality, fixes or any kind of power, are always welcome.
Oh, and btw, the sqlite databases structures (for mirrors and personal systems) are included in datastructs.h. If you have any questions, please ask here or mail me. :-)