News from theskeen.com:

Resident coder Emu_Kidid has released one fantastic piece of homebrew software. SD-BOOT allows you to boot homebrew and your legal backups using a SD -> GameCube adapter like the SD-Gecko. You can find more information and help test the software and add to the compatibility list by visiting it’s official release thread.

http://www.tehskeen.com/forums/showthread.php?t=5832