Now IPv6 tunnelling works

But don't ask me what I did differently, because I don't know that I did anything. Perhaps it was some kind of server problem at freenet6.
I did dig up this alternative guide on how to set up IPv6 tunnelling in Ubuntu but it really is very little different from the one I used yesterday.
In any event, when I run
ifconfig tun
I now get this:

tun Link encap:UNSPEC HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
inet6 addr: 2001:5c0:8fff:fffe::ad4d/128 Scope:Global
UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1280 Metric:1
RX packets:5 errors:0 dropped:0 overruns:0 frame:0
TX packets:1 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:500
RX bytes:352 (352.0 B) TX bytes:80 (80.0 B)

If I run

host ipv6.google.com

I get

ipv6.google.com is an alias for ipv6.l.google.com.
ipv6.l.google.com has address 208.69.34.132
ipv6.l.google.com has IPv6 address 2001:4860:0:1001::68

which shows that Googles IPv6 address is 2001:4860:0:1001::68

OK, so now I know how to set it up and use it but I'm still not sure I know what I can do with this great technological advance.

Incidentally, IPv4 browsing becomes painfully slow if you leave the IPv6 tunnel switched on. So, you'll have to stop it before getting back to some real browsing.
Here's another explanatory article on IPv6 and tspc from Univ. of Southampton.

Here's yet another very useful article on IPv6 tunnelling. This one deals with installing from source which is what I had to do in Foresight.