Hackmii has a story about a Wii recovery dongle that Team Twiizers has developed. The SaveMii is a small PCB that you plug into the GameCube memory slot that forces the Wii into recovery mode. This allows some manner of recovery by allowing updates from game discs to take place or running an autoboot disc if you have a drive chip installed.
Unfortunately, it still isn’t exactly the holy grail of unbricking a fully-bricked Wii. It will help to recover a semi-bricked Wii if you have installed an update on a disc from the wrong region. If you’ve managed to completely hose your Wii system menu, the dongle won’t help. Check the Wii troubleshooting page for details.