Hrmmm, Wii can use DVD9? So the Wii optic disc being a standard DVD instead of DVD9 means there may be Wii game optic discs in the future that are DVD9?
I believe I read several months ago that the Wii does actually contain a regular DVD9 player, it just doesn't have a hardware decoder. The initial plan was to have DVD ready out of the box, but Nintendo scrapped that to keep the cost down. Sonic Solutions (Roxio) was tapped to handle the DVD player component as far back as mid-2006, and this was confirmed by Sonic and even Nintendo. It's possible that DVD playback on the Wii could be as simple as a firmware release and a DVD player channel software download.