A new version of the first Dual Layer ISO image dumper that has been verified to work for the Nintendo Wii has been released ( http://nekokabu.s7.xrea.com/blog/2008/02/post_34.html ). Using Wii/GC Raw Image Dumper Ver.0.05 you can dump the “second” layer of dual layer Nintendo Wii discs and with a little work join them with the first layer to produce a working backup.
Thanks to brakken / http://www.tehskeen.com for the news.
http://psx-scene.com/forums/nintendo-news/64069-wii-gc-raw-image-dumper-ver-0-05-a.html