Manuel Kraus actually asked for an english response :)
the domain list is a discussion list about the Icelandic domain .is, usually considered for Icelanders :)
The question is 1) about IPv6 resolutions in a domestic setting and 2) Registration of IPv6 enabled DNS servers.
Hey, you have international customers, english please! ;-)
In brief: 1) IPv6 queries will work domestically if the client and server both provide IPv6 addressing and have sufficient connectivity to speak IPv6 between each other (based on IPv6 priority over IPv4).
2) ISNIC has enabled registration (glue records) for IPv6 enabled servers. IPv6 only servers can also be registered.
Since our upstream providers still classify IPv6 transit as "Beta", we're not really confident in saying IPv6 is enterprise ready - however it's been stable for some time...
ISNIC started working on IPv6 over three years ago, which shows you how slowly the upstream/transit providers are working towards IPv6 capabilities. Our website and mailservers have been IPv6 enabled for quite some time and any client with IPv6 connectivity is very likely to use it.