Just for the lulz I fired up a CentOS VM (I knew that Citrix XenServer would come in handy!) and configured a tunnel to HE via that.
I then configured a static IP6 address on eth0 and fired up radvd. My main Linux machine automatically picked up an address on that subnet and could ping6 to the outside world. I could also ssh from my linode directly to my main Linux machine (did I mention I need an IPv6 firewall?).
Heh, the Mac Mini also automatically picked up an address as well.
So it kinda just works.
The problem I have, though, is that the IPv6 addresses being assigned are based on MAC addresses but I have no easy association between that and the host. So ipv6 assigned via autoconf and router discovery may be fine for dynamic hosts, but not so much for servers. And for dynamic hosts there's not an easy association between the IPv4 and IPv6 addresses (eg dhcp214.home on IP4 is known; what's the equivalent IPv6 address?). So it looks like I need a DHCPv6 server instead, so give out known IPv6 address ranges, rather than allowing autoconf via router discovery.