Those of you who have imported the Xbox 360 version of Rock Band will be interested to learn that the US Official Xbox Magazine is cover-mounting a trio of exclusive add-on songs later this month.
The February 2008 issue, which goes on sale (sorry, "hits newsstands") on 15th January, includes Freezepop's "Sprřde", Bang Camaro's "Rock Rebellion" and Count Zero's "Shake", all of which can be installed to the hard disk for easy future access.
Joystiq has tracked down YouTube vids for a couple of them, and speculates that if discs can be used to stuff the hard disk with new content then Harmonix/MTV could potentially offer retail expansion discs along these lines. It certainly doesn't sound like it's outside the realms of possibility.
The game's creators have already established themselves as keen proponents of add-on content, having released over a dozen single-song downloads and several track packs on both Xbox Live and PlayStation Network since the game's late-November US launch.
For more on Rock Band, which is due out on PS3 and Xbox 360 in Europe in Q1 2008, check out our Rock Band import review.