|According to NintendoWiiFanboy Rock Band has an official release date of June 22nd, 2008 for the U.S. and Canada. $169.99 will get you a mic, drum kit, wireless guitar and game with a 63 song set list. For complete details head over to NintendoWiiFanboy.
According to a Harmonix Developer (hmxsean) "The feature-set is a lot closer to the PS2 version of Rock Band which was also developed by Pi Studios. We've decided to focus on getting the core gameplay on to the Wii and focus on making that awesome.The instruments don't use the Wiimote. They function the same as our peripherals on the other platforms."
Rock Band home page forums.
For a picture of Wii Drum Kit and many questions asked click Here to Joystiq