I have just concluded writing a couple of classes for KDE in the new project I am starting, regarding full IPv6 support. The classes are:
Those classes are simple and actually change nothing in current KDE's implementation of sockets. Next step is now to add class KExtendedSocket (probably inherited from QIODevice), which will do everything sockets need to do. After that is done, I'll rewrite KSocket from the scratch, keeping the same signature, to use KExtendedSocket.
Mail me if you want the files