Twitter’s #Music app is out at last for the Web and iOS, following an extensive rumor cycle. If you are behind the times, head here for a detailed explanation of the service. Data from the launch of #Music and the popularity of the various music services that it supports was recorded by the fine folks over at Simply Measured. Their filtered information indicates that among Twitter #music users, Spotify is the most popular music service, edging out iTunes. Here’s the full breakdown of 24 hours of #NowPlaying tweets that included musical links: Spotify: 11,984, iTunes: 11,612, Rdio: 3,457. All told, a total of 256,226 #NowPlaying tweets were pushed in the first 24 hours of the service’s life. According to Simply Measured, that is a rate of “four times the first 24 hours of Vine posts.” As #Music has a Web presence, which Vine does not, that it beat out the other service isn’t surprising.