Factor 5 have confirmed development for Wii via a job posting for a lead designer to work on the platform.
According to an entry on the company's careers page, the lead designer needs to be "responsible for one or more areas of design expertise in addition to designing and implementing levels for an upcoming Wii title."
Could Factor 5's involvement in a Wii title confirm the existance of Kid Icarus Wii, or will the team be involved in Star Wars: The Clone Wars?