You would think if Nintendo was going to get sued over the Wii, it'd most likely come from the numerous users who have chucked their Wiimote and had it damage an object in their house. However, the first lawsuit we hear coming since it's release is, of all things, over a button. A company called Interlink that specializes in interface devices is suing Nintendo over the Wii's Remote trigger, which they claim infringes on a patent they received 9 years ago.
Interlink goes on to state that it is seeking compensation for "loss of reasonable royalties, reduced sales and/or lost profits as a result of the infringing activities."
Nintendo's official response hasn't been released yet, if they will comment at all. Given the ambiguous nature of many patents of this nature, this could easily go either way.