I've moved the Japanese stub wiki (only a few pages) over to the new software; it's now set up at ja.wikipedia.org. At some point if the ja.wikipedia.com address can be reassigned to the new server, that'd be great.
The interface has never been localized, so it's (still) in English. If someone would like to help with a translation, I'd be quite happy about it. (I could convert all the English words to katakana, but that wouldn't be very helpful. :)
-- brion vibber (brion @ pobox.com)