The Green Day: Rock Band demo has been released on the Xbox Live Marketplace, and along with it is a teaser for Rock Band 3 at the end of the demo. The most exciting part is that an image is shown with the symbols for Guitar, Bass, Drums, as well as 3 mics since they have already announced harmonies will now be available in the full Rock Band series. On top of all that, there is a symbol with piano keys, suggesting that the keyboard peripheral is finally on its way to Rock Band 3.
This means that many of the upcoming songs in Rock Band 3 will most likely include a lot of keyboard parts to compliment this new controller that is bound to release with the third title in the Rock Band series.
Though there aren't any details on what this keyboard peripheral will consist of or how it will be used, we can be sure to see more details arriving on this addition in the very near future. That is, if Harmonix doesn't hold out on fully revealing it until E3 this June.