Why ?
First of all because the wii is a cool console, but second of all, because such an emulator could run on many different devices.
The PC would be the first target, should be no problem as it’s got bluetooth for the wii-mote, wifi/lan for the net connection, a screen and so forth…
But hey, why stop at PCs (windows/linux/mac), why not go ahead and port it to… the xbox360!
Yeah that’s right, a wii emulator for the xbox360 is theoretically possible. Once the xbox360 is fully cracked and homebrew apps can run on it, it should be possible to port a windows wii emulator to the 360.
The 360 sports bluetooth (yuval updated me that it doesn’t have bluetooth, so take everything i wrote and apply to the PS3 
, wifi/lan, screen, all you need…. now wouldn’t that be fantastic. imagine booting the 360, starting the wii emulator, then popping in wii-sports and playing wii games on your xbox-360… wonder if that would be legal. There used to be a Playstation emulator for Windows called Bleem, it sold legit but I think Sony gave them lots of trouble.
It may even possible to get a wii emulator on the PS3, who knows. this is a cool challenge.
here are the wii specs, and a comparison to the gamecube : http://www.wiili.org/index.php/Gamecube-wii-hardware
I’m not sure the XBox360 has Bluetooth. The PS3 does. Also the PS3 can run Linux, so theoretically you can write an emulator today. Bottom line, chances are higher that we’ll see a Wii emulator for the PS3 than on the XBox360.