Google has officially joined the ranks of Amazon, Apple and others in selling online music.

As expected, the online search giant announced late today the launch of its cloud-based Google Music, a service that was opened last summer to only early "beta" testers.

Like its competitors, Apple iTunes and Amazon MP3 Music Store, Google Music will allow consumers to purchase digital music for approximately $.99 to $1.29 per track as well as store and play personal music to any Net-connected device using Google's servers. Google's music store will sell its digital wares directly from the Google Android Marketplace store on smart phones and tablet computers.

Purchased songs are automatically stored in Google's computers which can be shared (along with other music stored on Google's cloud-based system) with others on Google's social network, Google+. Friends within a user's Google+ Circle, will be able to listen to each shared tracks once for free.

For now, the Google's music library offers about 13 million songs from three of the four major recording labels—Vivendi SA's Universal Music, EMI Group Ltd. and Sony Music Entertainment—as well as 23 independent music labels.

While Google Music cannot (yet) offer tunes from Warner Music Group and its artists, such as Cee Lo and Green Day, it offer offer consumers access to exclusive content— live concert albums from the Rolling Stones, Coldplay and others as well as the debut of Busta Rhymes' latest work.

What's more, Google's music service dangles an attractive price—free—to consumers. Google Music, which will be available to Android-powered devices in the U.S. "in the coming days," will not charge users for storing up to 20,000 songs online.

Google Music is open for business [Official Google Blog]