The Galaxy S3 supports IPv4 and IPv6 PDP so now you can 'dual stack'
APN setup instructions:
(Technically you have been able to do this for a couple of weeks but it was broken due to DNS issues-striped AAAAs, which was resolved yesterday)
Easiest way is to try it and then visit http://test-ipv6.com.
You should score a 9/10 (DNS server isn't dual-stacked, not a problem for now).