N-Europe is reporting that Nintendo will not only announce Mario Kart for Wii at E3, but they will also announce it coming out by the end of the year in Europe:

Mario Kart for the Wii will be a “replacement” for Super Smash Bros. Brawl in Europe, which will sadly miss Europe this year, and it will be out early 2008 instead. However, this also means that the US will not see Mario Kart until early 2008, and they will be getting Smash Bros. Brawl in 2007. This means that Nintendo fans in both Europe and the US will have something to moan about (they’ll have something to be glad about, too….but there will probably be more moaning).

This seems like a long-shot, but we’ll know for sure soon.  Stay tuned.