MTV Games and Harmonix are launching public beta for Rock Band Network today, reports Destructoid. The online music service is now open for registration by artists interested in turning their music into playable game tracks.  Citing company sources and the Wall Street Journal, Destructoid says popular artists already signed up to offer content include Billy Idol, Postal Service, Mudhoney, The Shins, Flight of the Conchords, Jonathan Coulton, Evanescence, Sleater-Kinney, some Finnish death metal, and Creed. Harmonix said the service will open once it has enough content, and will charge $1 to $3 based on prices set by track authors. Read more at Destructoid.