Rdio, the social media music streaming site launched by Skype and Kazaa co-founders Janus Friis with Niklas Zennström, went live Tuesday for users in the U.S. and Canada. The site was first introduced in early June, but has been an invite-only service since launch.

Rdio's real strength as a service largely revolves around its social media functionality, relying on the listening habits of users' friends for album recommendations, rather than the more standard computer algorithms based upon a user's own listening history.

In the past couple of months, Rdio has expanded its device offerings, with apps for the iPhone, Android, and BlackBerry. The service has also expanded its library and today announced that it will feature offerings from a number of independent publishers, including Arts & Crafts, IODA, IRIS, Finetunes, INgrooves and The Orchard. IODA's collection includes music from the London Symphony Orchestra, Ghostly International, and more.

Rdio (pronounced AR-dee-oh, the company insists) is also offering more curated selections with profiles from "music publications and influencers," like Spin Magazine, KCRW, Pitchfork, and The Fader.

The service runs $9.99 a month for unlimited Web and mobile music streaming and $4.99 for Web-only. You can check out a full hands-on review with Rdio over at Appscout.