They work just fine on system menu 4.0 and higher. Be aware however, that not all homebrew applications are currently compatible with SDHC. There also seems to be a file size limitation for playing Virtual Console games straight off of an SD card as well. For me personally, N64 and Wiiware titles will not play off an SD card, without first clearing space on the Wii internal memory and moving it over. This may have been rectified in system menu 4.2 though, I have 4.1 and refuse to update.