The missing content is "in the final testing stages," according to a post by community manager Sean Baptiste on the game's offical forum. "Harmonix is working as fast as possible to deliver the 20 free bonus songs for Rock Band 2, plus an additional 30 songs from the Rock Band DLC Catalog to fans as early in 2009 as possible."

Rock Band 2 Wii owners will eventually be able to purchase and download the "entire back catalogue" of Rock Band DLC, which includes hundreds of songs from various artists. Harmonix has yet to confirm pricing for Wii DLC, but it's expected to be in line with the PS3 and Xbox 360, where songs are typically sold for $2 a piece.