Translations always have to contain the URL, version number and copyright of the original document (but yours, too). Pls. don't translate the original changelog, this is not very useful - also do not translate the full section about available translations, can be run out-of-date, add an URL to this section here in the English howto.
Looks like the document's change frequency is mostly less than once per month. Since version 0.27 it looks like that most of the content contributed by me has been written. Translations always have to use the English version as source.
Note: an overview with URLs can be found at http://www.bieringer.de/linux/IPv6/.
A Chinese translation by Burma Chen <expns at yahoo dot com> (announced to me at 2002-10-31) can be found on the TLDP: http://www.ibiblio.org/pub/Linux/docs/HOWTO/translations/zh/Linux-IPv6-HOWTO.txt.gz (g'zipped txt). It's a snapshot translation, don't know whether kept up-to-date.
Since 2002-08-16 a Polish translation was started and is still in progress by Lukasz Jokiel <Lukasz dot Jokiel at klonex dot com dot pl>. Taken source: CVS-version 1.29 of LyX file, which was source for howto version 0.27. Status is still work-in-progress (2004-08-30).
With 2002-11-10 a German translation was started by Georg Käfer <gkaefer at gmx dot at> and the first public version was published 2003-02-10. It's originally available on Deep Space 6 at http://mirrors.deepspace6.net/Linux+IPv6-HOWTO-de/ (mirrored e.g. on http://mirrors.bieringer.de/Linux+IPv6-HOWTO-de/). This version will stay up-to-date as much as possible.
With 2003-04-09 a French translation was started by Michel Boucey <mboucey at free dot fr> and the first public version was published 2003-05-09. It's originally available on Deep Space 6 at http://mirrors.deepspace6.net/Linux+IPv6-HOWTO-fr/ (mirrored e.g. on http://mirrors.bieringer.de/Linux+IPv6-HOWTO-fr/).
A member of the MontevideoLibre, a project in Uruguay (South America) started the translation into Spanish in wiki format some time ago, but the URL is no longer available.
With 2003-10-16 a Italian translation was started by Michele Ferritto <m dot ferritto at virgilio dot it> for the ILDP (Italian Linux Documentation Project) and the first public version was published 2004-03-12. It's originally available on the ILDP at http://it.tldp.org/HOWTO/Linux+IPv6-HOWTO/.
On 2003-05-14 Shino Taketani <shino_1305 at hotmail dot com> send me a note that he planned to translate the HowTo into Japanese.
On 2004-06-18 Nikolaos Tsarmpopoulos <ntsarb at uth dot gr> send me a note that he planned to translate the HowTo into Greek.
On 2005-07-18 Necdet Yucel <nyucel at comu dot edu dot tr> send me a note that a Turkish translation is available. It's a snapshot translation (currently of 0.61) and can be found at http://docs.comu.edu.tr/howto/ipv6-howto.html.
On 2011-05-06 Gustavo Mendes de Carvalho <gmcarvalho at gmail dot com> start to translate the HowTo in Portuguese-Brazil. The first try in 2007 by Claudemir da Luz <claudemir dot daluz at virtuallink dot com dot br> was never finished.