This comes after information in EDGE Magazine said that Sega moved developers from their Playstation 3 section over to work on the Wii, so this would make sense. JeuxFrance said that Sega will be revealing a game that "that everyone waits (for)". That would mean that the game is fairly popular.
But what game would be coming out next? Doubtfully another Sonic game. It could be another game in the Phantasy Star series, or even Full Auto. Virtua Fighter could also come out, but I doubt that Sega would want to come out with a fighting game for the Wii until somebody else does it great first.
Who knows, maybe even Jet Set Radio. We will find out in the upcoming months.