Google Music, the company's cloud-based online music service, is now available to all users in the U.S. and includes song and album sales, as well as an integration with the Google+ social networking site.
Introduced in test form and by invitation only in May as a cloud-based song storage and playback service, Google Music will also let users buy albums and songs from all major music labels, except Warner.
Google Music users will be able to share the songs and albums they purchase with their friends on Google+, and those friends will in turn be able to listen to those songs and albums in their entirety, not just to samples, one time.
The songs and albums will be for sale in the Android Market, which is accessible via Android devices and Web browsers. Google Music is compatible with Android and Apple iOS devices, and can also be accessed from PC browsers.
"Google Music is about discovering, purchasing, sharing and enjoying digital music through integrated and personalized ways. It's about the cloud, the Web and mobile. It's about better connecting you with the music you own and introducing you to new music," said Google official Jamie Rosenberg at an event in Los Angeles on Wednesday that was webcast. .
"Last but certainly not least, Google Music is about artists and their music, and about new ways to connect artists with their fans," he added.
With this launch, Google becomes a direct competitor in online music to Apple, Amazon and others, joining a highly competitive and mature market years after other rivals.
Google Music looks solid as it prepares to face formidable competitors Apple iTunes and Amazon MP3, which are entrenched in the market with big user bases, said Michael McGuire, research vice president for media at Gartner.
"Google Music has the foundation of a nice store and service," he said.
Now, Google must find a way to attract online music buyers and convince them to make purchases in its store as well, and that's where the Google+ integration could be a big help, McGuire said.
"The barrier to entry is how many consumers will put their credit card in another store," he said. "If Google can leverage Google+ to drive people to its store, that could be an interesting differentiation for them."
There are currently about 8 million songs available for purchase through Google Music, a figure that will grow to about 13 million in the coming months. In addition to EMI, Universal and Sony, Google Music is partnering with more than 1,000 smaller labels.
It's hard to tell why Google hasn't been able to cut a deal with Warner, but the music label traditionally hasn't been quick to join online music initiatives, McGuire said.
About 1 million people participated in the service's trial, listening to about two-and-a-half hours of music on average every day, officials said. Users can store up to 20,000 songs in Google Music. The cloud storage and playback portion of the service is free.
Google Music also features exclusive content, including a live album from a 1973 Rolling Stones concert, several tracks from Coldplay and Shakira, the first single from Busta Rhymes' new album, and a live Pearl Jam album, among others.
At Google Music, artists who have the required rights to their music will be able to create their own pages, upload tracks and make them available for sale.
One element not included in Google Music is a subscription service like the ones offered by Spotify, Rhapsody and others, where people pay a monthly fee that lets them stream millions of songs in the service's music collection.
While Google could consider adding such a component to Google Music in the future, it's smart to start with the model of purchasing songs and albums "a la carte," McGuire said.
"As interesting as music subscription services are, they are complex to run," he said. "There are a variety of different licensing requirements you have to deal with. It's a very different kind of beast."
Juan Carlos Perez covers search, social media, online advertising, e-commerce, web application development, enterprise cloud collaboration suites and general technology breaking news for The IDG News Service. Follow Juan on Twitter at @JuanCPerezIDG.