This is about as direct a confirmation of downloadable content in the Wii version of Rock Band 2 as we're going to see. Even better, hey, free songs! The official Rock Band 2 site has started taking registrations for a set of 20 free downloadable bonus tracks, accessed by entering a code found on the instruction manual. Xbox 360 fans have been aware of this offer for a couple of weeks due to their, well, earlier access to instruction manuals. We didn't dare get our hopes up about any downloadable music, much less a bundle of free songs.
But the registration clearly says "Anyone who has purchased Rock Band 2 for the Xbox 360, PS3, or Wii is eligible to receive 20 additional DLC tracks, free of charge, coming soon"! Huzzah!