"Third, and this is a big one, there are no trademarks registered by Nintendo nor by any dummy corp in the U.S or over there for Wii. This is unprecedented for Nintendo and it is not possible that his is an oversight. If Wii were the name, they would have registered it. In fact, no new trademarks have been registered by Nintendo at all. This leads us to conclude that Nintendo has in fact registered the real name under a dummy corp, which is SOP when trying to keep a name a secret prior to launch.”
source :codename revolution