I've just published a first draft of BEP 32, which aims to extend the DHT to IPv6. It's on
http://www.bittorrent.org/beps/bep_0032.html
This is my personal proposal, and it doesn't (yet?) represent consensus of the BitTorrent community. Please feel free to comment at
http://forum.bittorrent.org/viewforum.php?id=25
--Juliusz