The end of the demo for Green Day: Rock Band showed off a mysterious addition: something that looked like a keyboard being added to the game's lineup. Now, an internal document sent to Gamervision by a source (who has been right on several occasions in the past) inside of Gamestop confirms that there is, indeed, a keyboard being added to Rock Band, and that it will set gamers back $129.99. While many might be quick to point out that Gamestop release dates aren't completely official, they're usually based on fact, and more times than not the company's news comes back being completely true.

We're fairly sure this is true, and would be shocked if Gamestop really jumped the gun and took a wild guess here. With E3 coming up (and Gamestop TV likely getting some exclusives to run during the show) they likely know more than they're going to admit, and this is likely something that simply fell through the cracks. There are listings for the Xbox 360, PlayStation 3, and Wii, as well, so don't expect anything left out here. It's also worth noting that we don't know if this bundle is keyboard only, or comes with additional guitars, drums, or microphones. Or keytars. 

We've contacted Harmonix for a response, and expect a rather quick "we don't comment on rumors or speculation." We'll be sure to keep you posted.

[Thanks, Mike!]