Nintendo has updated the Wii system software with the ability to download games directly to - and run them from - SD cards, and now supports SD cards larger than 2GB.
Although save-game data must be stored on the Wii, any channel - Nintendo's umbrella term for Virtual Console and WiiWare games, and other bits of software like the weather pages - should run from SD.
The line-up of content stored on your SD card is visible once you click a new "SD" icon in the bottom left of the Wii system software homepage, with up to 20 pages (240 titles) to fill.
A bit of experimentation reveals that games are temporarily transferred to the Wii's internal flash memory while they run. NES games load in a couple of seconds, whereas for bigger titles, like N64 games, it's closer to 15.
Today's update also introduces four old-days arcade games to Virtual Console, each priced 500 Nintendo Points (as we're probably supposed to start calling them). That's approximately GBP 3.50 / EUR 5.
For that you have your choice of Mappy (side-scrolling platformer), Gaplus (better known as Galaga 3), Starforce (a vertical shoot-'em-up) and The Tower of Druaga (a maze game running on modified Super Pac-Man hardware originally).