While there's no official word (trust me, they're in the same building as me, I'd know), Billy Joe, the lead singer of Green Day, broke the news on Kevin and Bean's Breakfast radio show on KROQ 106.7 FM, that they're collaborating for a "Rock Band" game.
It would certainly explain the lack of playable Green Day songs in either "Rock Band" or "Guitar Hero."
Billy Joe had this to say about the game's potential release date:
"I'm not sure...soon. Like I think not this week, but this year soon...by the end of this year."
Hmm...vague. We'll be checking in with Harmonix to see if they've got some more specifics.