From IGN's live blog:
"Finally, talking about an answer to save more content on Wii. Presumably the SD card access. Bill Trinen from NOA takes the stage to show off "a menu." An SD card icon is now located on the bottom-left corner on the WIi Channel interface. Click on it and it'll take you to a Wii Channel area that scrolls 20 times over, allowing you to save up to 200 games. Wii System Menu 4 is the name of this update and it supports high capacity SD cards up to 32BS. You can now download content directly to an SD card now. And you can also launch content directly off the SD card. Sweet gods, thank you! "