If client is logged in, Google bounces to the old site. In order to access over IPv6, you have to log out and use http://ipv6.google.com/webhp. Apparently, not quite there yet.
One funny thing, using Google while logged out is much faster. Apparently it takes time for them to act upon cookies my client sends. Remind me again how they goaded everyone into this "homepage" thing. Ah yes, Gmail.