A couple Wii hackers have found a way to glitch Zelda into running unsigned code. From the forum discussion at TehSkeen:
Yes, that’s right – an exploit for the Nintendo Wii has been discovered and it allows you to run custom code. The method is pretty simple. Copy over a save file for Zelda, load it and the code runs. Don’t get too excited yet. They have only been able to run 4 lines of code, but this is in a days work.
Right now I’m still having trouble reading through the forums due to all the attention this has been getting. I suspect it’ll be a little while before the dust settles and we find out the nitty gritty of repeating the hack and making it actually do something useful.
With any luck, this will lead to a small bootstrap loader that will allow homebrew Wii development to take off, similar to the glory days of the Dreamcast.