Google recently published that they are now available via IPv6. Nice idea.. but for now only available via a separate name: ipv6.google.com. They don't dare take the plunge yet of publishing an AAAA record for www.google.com. That would be really adopting IPv6 and finding those clients that can't deal properly with advertised IPv6 addresses without outside IPv6 connectivity.
I can understand that that change would have major implications. Indeed, clients being unable to reach it, Akamai needing to support it, load balancers to support it. But the announcement skips these important issues about really taking IPv6 into production and just says 'we do something with IPv6 now'. Yes, but you are not integrating it fully yet.