According to a report form NPD, the Rock Band franchise has sold over $1 billion in United States and Canadian retail sales.  MTV reports that part of that is over 40 million songs have been downloaded.
 
Originally launched on November 20, 2007, Rock Band is a music game platform that allowed music fans and gamers to interact with and discover music by choosing guitar, drums, vocals, or bass to start a band and rock the world. Developed by Harmonix, and published by MTV Games, the Rock Band platform has had a positive impact on the overall promotion and sales of music, benefiting artists included in the game both directly through royalties associated with game sales and indirectly by causing the sale of more songs and albums.

MTV has released key stats for the Rock Band Franchise

Sales

• Rock Band franchise has officially surpassed $1 billion dollars in North American retail sales in 15 months, according to the NPD Group
• Rock Band was the #1 title of 2008 by revenue across all game genres (NPD)

 
Music / Downloadable Content

• 614 songs offered via the Rock Band platform, both on-disc and in-game music store, as of March 24, 2009
• 269 different artists / bands offered via Rock Band franchise as of March 24, 2009
• Over 40 million paid songs have been sold via download since Rock Band launched on November 20, 2007
• 11 albums released to date via the Rock Band platform including AC/DC Live, The Cars, Judas Priest,Pixies, Mötley Crüe, Foo Fighters, Red Hot Chili Peppers, Megadeth, Rush, No Doubt and Stevie RayVaughan, as well as special compilations from The Who, Nirvana, The Grateful Dead, Boston and more

 
Critical Acclaim

• Average Metacritic score of 92[2] for both Rock Band and Rock Band  2  
• Rock  Band and Rock Band 2 have garnered more than 50 industry awards including:
• IGN’s “Best Music/Rhythm Game of 2008”
• Gamespot.com’s Editor’s Choice Winner for “Best Rhythm / Music Game of 2008”
• Spike TV’s 2008 Video Game Award Winner for “Best Music Game” and “Best Soundtrack in a Game”·        
• Gametrailers.com “Best Music and Rhythm Game 2008”·        
• PlayStation: The Official Magazine’s “Best Rhythm Game of 2008”
• Yahoo’s “Best Party Game of the Year – 2008” and named one of Yahoo’s “Best Tech Products of 2008”
• G4 TV’s X-Play “Best Music Game of 2008”
• Named as one of Entertainment Weekly’s “Entertainers of the Year 2008”
• Called “Best party game of the year” by the Associated Press
• Named as one of USA Today’s “Top Video Games of 2008”
• Cited as one of MSNBC.com’s Top Video Games of 2008 and one of the Best Xbox 360 Games of 2008
• Heralded as “hands down the best party game ever” by Time magazine and named as one of Time’s
• Top Video Games of 2008 Rock Band Franchise Innovations
• First full band music video game to hit consoles
• First music video game to offer export of content library from disc and cross compatibility of
• downloadable content (DLC) in sequel games.
• First music video game to offer weekly downloadable content (averaging more than 3 songs per week since its launch on November 20, 2007)
• Lead the way for full compatibility and interoperability between competing peripherals
•  First music video game to allow for export of avatars and other game data to create real life merchandise
• First music video game to offer full albums as downloadable content: Judas Priest’s “Screaming for Vengeance,” released in June 2008
• First music game to offer a new song day-and-date with its release to radio, with Mötley Crüe’s “Saints of Los Angeles”

 
For more information about Rock Band, please visit www.rockband.com