Apple owners where responsible for a surprisingly large number [0.238 percent ] of IPv6 enabled google users. Thanks to the wizards at Cupertino, who decided on Infinite wisdom Loop to meddle with mDNSResponder so now it cancels the queries and shuts down the socket after the first responses are in. Big change these are A responses so the AAAA replies will be /dev/null'ed leaving the end user [application] with no option but to access the resource via... IPv4.
Mistakes happen, but with 10.6.2 the issue is still here.
The DHCPv6 client is not available for MAC users either, that does not help since it's basically required to play nice with ISP's and other large network operators [large[r] companies come to mind]. Neither is there a lot of documentation on the IPv6 implementation.
Finally improving the Apple Airports with [more complete] IPv6 support is a good thing... unfortunately: it is a New Feature and as such, will NOT be available for us loyal Apple hardware buyers. Only the currently for sale AirPort Extreme & Time Capsule are lucky enough to have this 'New Feature' so you're out of luck if you thought you could snatch up a 'cheap' AirPort Express: they do not have it.
So IPv6 on my beloved Apple setup is basically broken and the future looks dim. Microsoft is miles ahead with working IPv6 since Vista. Thank G*d not to many people read this since otherwise the street credibility of OSX would be down yet another point. Microsoft's DirectAccess could develop into the first IPv6 'killer app' and that both makes me happy [IPv6 FTW!] and sad: why my BSD based OS is not leader of the pack is beyond me, except that maybe, just maybe, IPv6 is really not as much in demand as I -think- hoped it was.
As a desert, I offer you a link that I missed before, but certainly love as much as a lot of the other work of the author.