Seven songs being delisted from the Rock Band music store. http://www.rockband.com/blog/information-about-rock-band-dlc-re-licensing
"Bullets & Guns" and "Moving to Seattle" are part of the MTV2 Pack, "Hier Kommt Alex" is not playable on Rock Band 3 (and I'm pretty sure it's already been delisted), and "Promised Land" is free (it's a tie-in to that Rainn Wilson movie nobody saw).
You have a month to pick them up.
Wait, won't that make the Free DLC achievement unobtainable for RB3? Or was that just a goal? I forget..