I was checking out my twitter account tonight and ran into something. On a post from Insomniac’s Twitter page they were talking about Blue Oyster Cult will be coming to Rock Band. They also mentioned that a cow bell was in prototyped for the Blue Oyster Cult. The next tweet stated that Harmonix had mentioned it to the poster. I’ve copy and pasted the tweets below.

yes harmonix told us :) about 1 hour ago from mobile web
   
just learned that cowbell was actually prototyped for blue oyster cult rock band edition...as it should be.about 1 hour ago from mobile web

As a fan of Blue Oyster Cult this would be really cool. Whether this would be a DLC or an actual packaged game such as the AC/DC remains to be seen.

At this time I can not get a confirmation, but stay with Gamers Daily News for the latest news.