As much as I hate to nit pick one specific company, but Amazon Web Services is used by a LOT of people and groups, are they going IPv6? I know their Elastic Load Balancer is, but what about everything else? Is Route 53 v6 glued? v6 accessible?
More importantly what about CloudFront? Try going v6 only now and you'll have a lot of "functional" websites which look like hell because they use Akamai or CloudFront which aren't v6 enabled (Though Akamai has commited)