For those who are interested, some of the .US and .BIZ TLD nameservers have IPv6 glue.
Three of the 6 .US nameservers have IPv6 addresses:
i.gtld.biz has AAAA address 2001:503:d1ae:ffff:ffff:ffff:ffff:ff7e
j.gtld.biz has AAAA address 2001:503:a124:ffff:ffff:ffff:ffff:ff7e
k.gtld.biz has AAAA address 2001:503:e239::3:1
({a|b|c}.gtld.biz do not have IPv6 addresses)
Two of the 8 .BIZ nameservers have IPv6 addresses:
g.gtld.biz has AAAA address 2001:503:7bbb:ffff:ffff:ffff:ffff:ff7e
h.gtld.biz has AAAA address 2001:503:8028:ffff:ffff:ffff:ffff:ff7e
({a|b|c|d|e|f}.gtld.biz do not have IPv6 addresses)
- Dan