A new WiiMusic video, although it is in Japanese... Link
"Nintendo has finally provided gamers with details on their musical venture for the Wii, cleverly (and tentatively) titled Wii Music. Wii Music uses the Nunchuk and Wii Remote in time with button presses to control a six person band. Forty instruments will be available on which one can rock out, with four-player support and single player options available. The single player mode will let a Wii owner command up to four musicians simultaneously. If that's simply too much for you to handle, the CPU can control the remaining five if you want to dedicate yourself to a solo performance.
Wii Music is on beat to ship in 2008 in Japan, but we won't know a North American or European release date for a while." Link