According to URL:http://www.microsoft.com/windowsserver2003/technologies/ipv6/default.mspx XP should already contain what is needed, so it doesn't seem to be an issue anymore. Maybe you have to do something slightly creative to avoid a dependency on the "getaddrinfo" symbol on systems that doesn't have it, but GetProcAddress can typically be used to handle such eventualities.
/ Marcus Comstedt (ACROSS) (Hail Ilpalazzo!)
Previous text:
2003-04-22 13:48: Subject: Re: [caudium-general] ipv6 support
There were som issues with finding ipv6 drivers for Win* IIRC.
/ Peter Lundqvist (disjunkt)