Shiny US guitar pop boyband The Jonas Brothers are debuting their new single on Facebook tomorrow, a move which could bring new attention to the site for the American tween / teen demographic and will shine a light on what is possible in terms of promoting music acts through Facebook. The band will use a Ustream webcasting application to perform their new song “Paranoid”, (unfortunately not the Disney Christian-rock band’s cover of Black Sabbath”s classic of the same name. We’d like to hear that).Facebook’s in on the deal too, stating that “this marks the first time a US musical artist is debuting a new song via a live webcast series on their Facebook page.” Hopefully a sign that Facebook will be paying more attention to the role of music in its service. It’s also quite telling that the Jonas Brothers, whose faces were used to promote the launch of MySpace Music, have chosen to move across to MySpace’s main rival for this new campaign.It’s becoming apparent that US labels are disappointed with the performance of MySpace Music. CNet has cited a “source with knowledge” of talks between MySpace management and the major record labels with whom MySpace Music operates as a joint venture; the source claims that “several key players were unhappy” and are pushing for MySpace “to do more to integrate the service with the regular MySpace site.