http://www.internetsociety.org/deploy360/resources/case-stud...
And RFC 6877 specifies 464XLAT:
http://tools.ietf.org/html/rfc6877
and here is even more detailed info from T-Mobile:
https://sites.google.com/site/tmoipv6/464xlat
Regarding DS-Lite, this video from RIPE NCC provides a nice overview:
http://www.ripe.net/lir-services/training/e-learning/ipv6/tr...
Both DS-Lite and 464XLAT are ways that an ISP can be IPv6-only yet still access legacy IPv4 content and services.
EDIT: Apparently it's DS-Lite: https://news.ycombinator.com/item?id=6818805