Posted for the second time, thanks to the rollback...
It seemed likely that Sonic was going to be one of the other confirmed guest characters for the next Smash Brothers, and today it was confirmed at a Nintendo press conference in Japan. The Dojo, the official Smash Brothers site that reveals new content every weekday, now has the Sonic info as well as two new movies. This was always the game I said would be worth me buying a Wii, though I ended up with one anyway long before I felt there were games worth buying it for.
Other Wii news, mainly from the press conference: The Mario and Sonic Olympics game will support Miis; Mario Kart Wii will include bikes; Monster Hunter 3 moves from Wii to PS3 due to the PS3's high development costs; several games - Pokémon Farm, Dr. Mario, a Final Fantasy Crystal Chronicles title, Mojipittan Wii, Bomberman, Star Soldier R and Joy Sound Wii - are revealed for the upcoming Wii Ware (Wii Software) service, and there will soon be a DS download channel for demos, special content and... stuff.
It's all being translated from Japanese at the moment but it all seems fairly accurate. No word yet on how many years it will takes all this to filter through to Europe.