Following a limited rollout last week with music artists and influencers, Twitter's new #music discovery service is now open to everyone either as a web app at or a standalone iPhone client. As you'd expect from the microblogging social network, the new service helps users discover music based on what the people they follow are listening to and tweeting about, as well as recommendations from popular artists.

The app is centered around five tabs: popular, emerging, suggested, #nowplaying, and me. The first two are all about what the collective 'Twitterverse' is jamming to and surfacing "hidden talent found in tweets", while the other focus on your personal music taste based artists you follow and the #NowPlaying hashtag in your timeline.

Upon signing in with your Twitter credentials you'll be presented with artwork for songs in a tile-based interface along with options to follow the artist, tweet songs and start the player. Each track defaults to an iTunes preview with the option to buy the full version, although if you have a Spotify or Rdio account, you can link them to #music and access the full song. Twitter promises that integration with more services is coming.

Right now, the service is available in the US, Canada, the UK, Ireland, Australia and New Zealand. But the company hopes to include more countries in addition to launching an Android app over time.