Comcast is only one ISP. AT&T hasn't yet deployed IPv6 for their residential customers. (I think there are ipv6rd routers available, but you have to know about them and configure your own router to use them, and since it's not an official service, it could be discontinued at any time).
Then there's software. Many web apps don't support IPv6 (db fields limited to ipv4 format, or code assuming ipv4 format). For instance, Internet Brands is too busy with important business, like frivolous lawsuits, to fully support IPv6 in vBulletin. [1]
Some webapps have 3rd party hacks (or even first party hacks) to "support" ipv6 without modifying a lot of ipv4-dependent code, typically by hashing the ipv6 address, taking 32 bits, and using that as the ipv4 address. It's both disgusting and funny.
There's a long way to go before IPv4 is dead.
[1] http://tracker.vbulletin.com/browse/VBIV-9397 (you need a vbulletin.com forum login, unfortunately, and maybe also a linked license; in summary, it's a 2-year-old bug for full support of IPv6, it has no comments from vbulletin devs and no assignee.)
Then there's software. Many web apps don't support IPv6 (db fields limited to ipv4 format, or code assuming ipv4 format). For instance, Internet Brands is too busy with important business, like frivolous lawsuits, to fully support IPv6 in vBulletin. [1]
Some webapps have 3rd party hacks (or even first party hacks) to "support" ipv6 without modifying a lot of ipv4-dependent code, typically by hashing the ipv6 address, taking 32 bits, and using that as the ipv4 address. It's both disgusting and funny.
There's a long way to go before IPv4 is dead.
[1] http://tracker.vbulletin.com/browse/VBIV-9397 (you need a vbulletin.com forum login, unfortunately, and maybe also a linked license; in summary, it's a 2-year-old bug for full support of IPv6, it has no comments from vbulletin devs and no assignee.)