As with much of tonight's news, the revelation came during the Spike VGAs.

Exactly when the game will arrive remains unknown, as does its platforms--PlayStation 3, Xbox 360 and Wii are likely given past entries in the franchise--though it doesn't come as a surprise, as Harmonix has previously promised a Green Day "project."

Update: Harmonix has confirmed that Green Day: Rock Band will hit PS3, 360 and Wii in 2010, adding "the track list will be fully exportable, giving players the opportunity to play the songs in Rock Band and Rock Band 2 on the Xbox 360 and PlayStation 3."