From the Rock Band Blog:
 

"Hey Rock Band fans! Though we’re making a lot of noise this week with the announcement of Dance Central 2 at E3, we haven’t forgotten about you. As promised, we have tons of great new music coming to Rock Band over the next couple months. If dancin’ isn’t your thing, no need to worry: we’ve still got you covered.

Coming soon

AVENGED SEVENFOLD! You guys asked for it, and we have more Avenged Sevenfold coming to Rock Band – one song from their latest album Nightmare, and one classic fan-favorite A7X track.

Poison! You demanded more hair metal, and here it is! Get out your hairspray and eye liner because we have a most excellent three-pack of hits on the way from the ‘80s band.

System of a Down! Two of the most often requested tracks from the metal band will finally be coming to the Rock Band Music Store, and one of those two songs will feature their first Pro Guitar/Bass upgrade available for RB3!

Soundgarden returns to Rock Band! An unstoppable six-pack of classic songs from the seminal grunge band will be coming your way, with most featuring Pro Guitar upgrades.

And that’s just a sample of some of the music that will be available this summer! There are even more tracks from some of your favorite bands on their way, so stay tuned to RockBand.com, follow @RockBand on Twitter, or become a fan on Facebook to make sure you’re up to date with all the latest DLC news!"

Jesus. Is it really so difficult to put good bands in video games anymore? :(

Just give me Keyboard support for those 18 Grateful Dead songs that I dl'd for RB2 and I'm happy.

Hurry the fuck up and put some fucking Zeppelin on this fucking game!

Hurry the fuck up and put some fucking Zeppelin on this fucking game!

@MideonNViscera said:

Hurry the fuck up and put some fucking Zeppelin on this fucking game!

If they ever do Zeppelin, it'll be in an individual game like The Beatles RB. It'll also never fucking happen because Rock Band is no longer such a sweet get that it's worth putting your masters out for them.

Excited for the Poison and Soundgarden. Don't really need any more SOTD and never needed more A7X than Beast and the Harlot and Bat Country to begin with.

@MideonNViscera said:

Hurry the fuck up and put some fucking Zeppelin on this fucking game!

If they ever do Zeppelin, it'll be in an individual game like The Beatles RB. It'll also never fucking happen because Rock Band is no longer such a sweet get that it's worth putting your masters out for them.

Excited for the Poison and Soundgarden. Don't really need any more SOTD and never needed more A7X than Beast and the Harlot and Bat Country to begin with.

@MideonNViscera: Then masters are all they have, and they've been super wary of giving those out since some of the important ones got ruined in a movie deal. Also, each and every living member CAN still perform pretty damn well, though Plant doesn't sound like old Plant at all anymore.

Harmonix pulled a Buffalo Bills and just went 0 for 4 and broke my heart.