OCN, an ISP company in Japan has published an experimental service for non-IPv6 enabled devices in non-IPv6 enabled networks to access pure-IPv6 Home network.
They seems using some kind of tunneling service.
OCN IPv6 Mobile Provides Access to IPv6 Home Network from Mobile Terminals http://www.ipv6style.jp/en/news/2006/0214_nttcom.shtml
OCN IPv6 モバイル http://www.ocn.ne.jp/ipv6/mobile/?ipv6_info