Now available in the Apple App Store is a Green Day centralized version of the popular iPhone app "Tap Tap Revenge." Tap Tap is much like Guitar Hero or Rock Band except it's made for the iPhone and/or iPod touch. It will have ten tracks from the band, including "Welcome to Paradise," a live version of "21 Guns," amongst others. The app is $4.99 in the US and can be purchased by clicking here.
Click here to purchase and download the app for iPhone or iPod touch.
Update: Thanks to Michael who linked to this video of the game in the comments.