iOS/Web: Twitter has officially announced its music app, Twitter #Music. The iOS and webapp aim to help you find and listen to new music based on who you follow on Twitter.
The central focus of Twitter #Music is to help you discover new music. You can look through the Popular page to see all the music that trending on Twitter, the Now Playing tab to see what people you follow are tweeting about, or the Suggested tab to see suggestions based on who you follow. By default, the app lets you access full tracks for purchase in iTunes; if you're logged into Spotify or Rdio, you can start playing tracks in full.
As you'd expect, you can also tweet out anything you find. Both the webapp and iPhone app are available right now. Twitter is also planning an Android and iOS version. The app is based on technology from Australian startup We Are Hunted, which Twitter recently acquired. It isn't available worldwide, but fortunately Australia is one of the handful of countries supported in the initial release (along with the US, UK, Ireland, Canada and New Zealand.)
Twitter #Music (free) [iTunes App Store]