Technically the new firmware doesn't run things from the SD card, though. It just automates the process of copying from the card to the Wii, and then deleting it from the Wii when you're done.
There still needs to be enough room on the Wii's internal memory memory, and if size was that much of an issue, then using the SD card would take a really long time, since it would have to copy the entire game every time you run it.
