The musical rythmn game Samba De Amigo was also worked on by SonicTeam, so it's not much a wonder that Sonic would be able to make a cameo appearance there. With this screenshot you can see him dancing near Amigo, the cubic monkey & star of the game. They're in a Sonic 1 like Green Hill type of setting, complete with totem pole, sun flower, loop, and ring monitor. In the background you can spot some wii miis and even a Chao. It's cool to see they've worked Sonic in once again!
Info:In Career mode, after beating normal mode you unlock hard mode. The first set of Songs in hard mode is called "Sonic's challenge". Sonic's challenge consists of the
songs "Mambo #5", "Low Rider" and "Un Aguardiente". All three songs take place in green hill zone and have Sonic dancing alongside Amigo. The Chao appear in multiple other levels sometimes driving flying saucers. There is also a set of Sonic dance sounds that can be unlocked if you clear the song "Jump In The Line" in Amigo's Challenge.