A while a go it was found out that a buffer ovlerflow was exploitable int he Wii game Legend of Zelda - Twilight Princess, this exploit would allow hackers to run software from an SD card, opening up the homebrew market.
I was soon to write a post about how it works and how I got my Wii to boot Smash Brothers Brawl from a US disc (I live in the UK).
Sadly this plan has been stopped partially by Nintendo, their latest software update stops this exploit byy searching for and deleting exploited Zelda save games.
If you have any interest in cracking your Wii to run homebrew (including things such as a SCUMM emulator) then DO NOT update your console today.