[source: emu_kidid @ gc-forever.com] In case anyone has missed the news in the Game Boy Interface thread, there has been further development on making use of a pre-existing Super Smash Bros. Melee memory card exploit to load homebrew on GameCube. Thanks to Extrems who co-developed the changes with Dan Salvato, users can now load DOL files that are stored in .gci format on a memory card (primarily developed for loading the Game Boy Interface DOL). This is great news since it has opened up another way to load arbitrary homebrew which will come in handy for users who do not wish to modify their systems, and especially after the recent sold out status on the SD Media Launcher for the NTSC region.
The SSBM exploit will require a way to get a custom save file onto the memory card ahead of time (either a GameCube that can already boot homebrew or a backwards compatible Wii) & GCMM, along with a copy of the game (all regions supported).
You can try out the SSBM exploit from here, and then grab the Game Boy Interface .gci files from the official release thread.