According to IGN, it is official that factor 5 is developing a game for the Wii.
January 14, 2008 - The maker of the hit GameCube series Rogue Squadron is back. In a phone conversation with IGN Wii this morning, company president Julian Eggebrecht confirmed that the studio is underway with at least one all-new Wii project -- and it's not a Virtual Console game. Beyond that confirmation, Eggebrecht was mum, but he did note that the new title would not simply re-use old Rogue Squadron tech; whatever it is, significantly updated or even completely new tech has been developed to help accommodate it."
http://wii.ign.com/articles/845/845353p1.html