The next version of the IP protocol, which has been "nearly here" for years and years now. It's fairly trivial to use and configure, but suffers from an utter lack of popular services (not to mention client application support). Mac OS X and Windows XP have painless configuration and 6to4 support.
- RFC:2460 - Internet Protocol, Version 6 (IPv6) Specification
- Teredo Background (IPv6 tunnelling over UDP)
Things Missing
- DHCPv6 for some specific purposes (auto-configuration solves most problems).