I found something interesting. This was on the Gametraders Australian website under the 'consoles' page for the Wii.
Backward Compatibility: Revolution will play all of your favorite Nintendo GameCube games. An innovative self-loading media bay will play both 12-centimeter optical discs used for the new system as well as Nintendo GameCube discs. You can also equip a small, self-contained attachment to play movies and other DVD content.
Is that just old data or is there supposed to be an attachment for Wii avaliable already?