It looks like Nintendo will be sticking with the power brick they provided with the GameCube, or something similarly sized. The grey color looks better than the black of the GameCube, I think, and regardless of it all, at least we need not worry that it will cause a hernia when trying to lift it. Thankfully, it looks like the cord is longer on the Wii's power supply, also.
Honestly, I'm wondering why this didn't come up during E3. Also, why didn't I think of taking a picture of the Wii's power supply? With the recent Wiimote shots from the Spanish event and naughty peek under the flap, the Wii has been enjoying the attention of the paparazzi lately.