Nintendo Releases the Wii

The console was known by the codename of "Revolution" until April 27, 2006, when it was renamed Wii, spelled with two "i"s to imply an image of players gathering together, as well as to represent the console's controllers. It is said Wii sounds like 'we', which emphasizes that the console is for everyone. Wii can easily be remembered by people around the world, no matter what language they speak. No confusion. No need to abbreviate. Just Wii"

http://www.thegameconsole.com/videogames01.htm