Green Day released a brand-new album called Green Day ¡Uno! today, and the first single, "Oh Love," has also been released into the Rock Band Music Store! They've also released four songs from Green Day Rock Band as separate DLC: "Bran Stew/Jaded," "Good Riddance (Time of Your Life)," "Warning," and "Minority."
All five songs are available as "Green Day Pack 03," or separately for $2 each if you'd rather pick and choose. None of them have the optional Pro Guitar and Pro Bass upgrades, and only the new "Oh Love" has keyboards. (Honestly, I think they could've gotten Green Day fans to double dip if they'd added keyboards instead of just releasing them straight...)