While doing some blog surfing, I came across this interesting item.
Official Rock Band Drum Silencers.
It looks like the release date is April 18th, with a retail price of $19.99.
Update: Average Joe Gamer has some more info on their website, including a link to the product at EBGames/Gamestop 
Related Links:
Rock Band Silencers

Alright, here’s the rumor that we’re starting today…
Tomorrow, Rock Band developers Harmonix will likely announce the release of the first full album download for Rock Band.
That’s right… we went there. And here’s our reasoning…
Clue #1
On Friday, the following post was on the official Rock Band Forums
Post Title: Nothing to see here - (DLC […]