464XLAT Explained
IETF recently published RFC 6877 (464XLAT) describing a dual-translation mechanism that allows an IPv6 host (or CPE) in an IPv6-only access network to pretend it still has IPv4 connectivity. Why would one need a kludge ingenious solution like this? In a word: Skype.
For more details, watch the video explaining the need for 464XLAT and two typical use cases: Android handset and a CPE device (example: SOHO router with 3G uplink).
Unfortunately content providers don't need to switch as fast as they should to IPv6 services (our provider translate that for us... we still have 50 years for that).
http://www.internetsociety.org/deploy360/blog/2013/04/video-464xlat-live-demo-at-world-ipv6-congress-in-paris/ (video embedded at the bottom, after the description of what happened there).
Cheers, Jan Zorz