"Speaking to Computer and Video Gamers today, a Nintendo rep confirmed that the USB ethernet adaptor which was announced at TGS 2005 will indeed be coming out for the Wii at the console’s launch in December."
i think 3rd party adapters wont work unless its specifically for the Wii, im sure the Wii has drivers in the firmware to use a adapter like this for the future when their released, for now either dont bother because wireless is easier and getting less expensive, deifinitly woth not having to run cables trow ur house.