[Update 2: This problem has been fixed with the Wii's first downloadable system update. Wii saves are now transferable to SD cards.]
With all our Zelda playing this weekend taking place on one Wii system, we were eager to transfer the game save to our personal SD cards so as to avoid repeating completed dungeons on our own, personal systems. Unfortunately, the system software doesn't seem to support copying save files to an SD card, despite information to the contrary in the manual.
Page 39 of the Wii channels and settings manual clearly tells you how to "copy and delete data found on the Wii System Memory and SD cards," but our tests have shown that the SD card simply doesn't register on the memory management screen. We've tried this with a number of SD cards, both empty and full of data, and while picture viewing and MP3 playback worked fine, the system refused to recognize the card as a game save storage device.
This apparent oversight could well be fixed with a pending system update, and the Wii system does indeed try to update the system software when it signs on to a WiFi connection. But with the Nintendo Wii servers down until later this week and Nintendo representatives gone for the weekend, this is hard to confirm at the moment. We'll contact Nintendo for clarification and update as warranted, but as it stands now, it seems that our Wii game saves are stuck on the system that birthed them.
[Update 1: In response to commenters' questions, GameCube saves can not be transferred to either SD card or internal memory, though they can be copied back and forth between the two GameCube memory card slots.]
