Fantastic post on Debian Administration about miredo, a brilliantly-simple way to get a teredo virtual interface running on your machine, allowing you to transparently tunnel IPv6 over IPv4 without having to use a more complicated tunneling scheme (the article kvetches about 6to4). Still one or two comments are a little bit critical of the teredo approach and suggest other things over miredo (one mentions AYIYA). A brief search also yielded options like 6tunnel. Maybe now it’ll be worth connecting to Freenode and others using IPv6!