LOS ANGELES – With sights set firmly on its Silicon Valley nemesis Apple, Google launched its music service at an event in Los Angeles on Wednesday. The move into the space signals Google’s aim to challenge the mighty iTunes head-on.

The service update integrates a music section into Google’s Android Market, Google’s media hub for Android devices. Users can now purchase songs through the Android market, and can stream them wirelessly to their Android phones and tablets using the Google Music app.

In conjunction with the Market launch, Google opened its previously limited app — Music Beta — to public admission for those in the U.S. The service, now dubbed Google Music (shedding its Beta moniker), will be free.

In a tie-in to another of Google’s flagship products, the company is integrating the music store into its newly launched social network, Google Plus. After purchasing a song from the Android Market, users can choose to share the song within their stream of updates on Google Plus. That users’ friends can then listen to the entire track once for free.

Google has had issues in the past with its Android Market, with app developers and media providers complaining about not being discoverable inside of Google’s store. In an attempt to curb discovery problems, music interface menus will feature recommendations based on the music library of the user.

In order to entice new adopters, the company will launch a series of Google Music-exclusive tracks, including live sets from the Rolling Stones, Coldplay and Busta Rhymes.

Google fired its first shot in the music wars by launching its Music Beta program at the company’s I/O developer conference earlier this year. The cloud-based music locker service allows users to upload their existing music files from their computer to Google’s servers, which can then stream songs wirelessly to any desktop or Android device running the Music Beta app.

Google has its work cut out for it. Apple launched its iTunes music service over a decade ago, followed by the introduction of its revolutionary MP3 player, the iPod. The iPod’s immense commercial success — hundreds of millions of devices have been sold — drove iTunes user growth, feeding Apple what may be its biggest weapon: countless user credit-card accounts.

Google doesn’t have Apple’s cache of card numbers. To compensate, Google is going through the carriers. T-Mobile customers can purchase songs through the Android Market using direct-carrier billing. So essentially, all of the tracks a T-Mobile customer buys will show up on their monthly phone bill. While that only reaches the smallest carrier in the U.S. market, it’s still a significant base of credit-card accounts.

Amazon debuted a cloud locker service earlier this year similar to Google’s, nee Amazon Cloud Drive. This service has thus far had a leg up on Google, however, as users can purchase tracks from Amazon’s proprietary MP3 store, thus negating the need to upload tracks from local storage to the cloud.

All three services, however, contain at least one feature that the other lacks. And importantly, Apple and Google both already have hundreds of millions of MP3-playing devices out in the field. Amazon’s Kindle Fire, while capable of playing music, debuted just this week. Google has the obvious advantage over Amazon here, but there’s still a need to catch up to Apple.

“Any competition to iTunes is ultimately an ecosystem and devices question,” said Arash Amel, digital media research director for IHS Screen Digest, in an interview. “One key issue surrounding the Google proposition is how much of an Android ecosystem it is serving, and how well it can provide a comprehensive alternative to iTunes for Android users.”

iTunes also has another key feature that both Google and Amazon lack. Launched on Monday, the iTunes Match service allows users to bypass uploading their music tracks to Apple servers by scanning your library and ‘matching’ your tracks to those already available in Apple’s cloud.

For example: If Apple has the track, you can either stream it or download it to any iOS device or desktop using your Apple ID. If Apple doesn’t recognize it, you can upload your track to Apple’s servers, still letting you stream the song to any of your devices. Essentially, it bypasses the arduous task of uploading your entire music library which, depending on the size of your collection, could take hours, days or even longer.

But Apple’s music service still lacks a major capability found in both Google’s and Amazon’s offerings: Streaming playback. While iPods and iPads still require users to store their music locally (i.e. on the old-fashioned internal hard drive), Google Music allows for both streaming and local playback.

Apple’s iTunes costs $25 yearly, most likely a charge that sates the record labels for revenue sharing. Google — whose music service is free — positions that charge differently.

“Other cloud music services think you have to pay to listen to music you already own,” said Jamie Rosenberg, Director of Digital content for Android. “We don’t.”

Further, Apple has reached iTunes distribution agreements with all four of the major U.S. music labels. Google has only 75 percent of the labels signed on at launch, with Warner Music Group being the sole holdout. The company has also tacked at least 20 smaller, independent labels.

A lack of support across all of the labels could seriously limit Google’s music library offering.

“Launching without the support of every label, in this day and age, is unthinkable and will stymie their competitive edge against even Amazon’s music services,” said Amel.

A Warner Music Group spokeswoman declined to comment.

In an appeal to smaller acts, however, independent artists will be able to sell their own music — sans label — through the Google Music store.

“If you are an independent artist with original content, we’ve got your audience,” said Chris Yerga, director of Android cloud services at Google.

If Google can successfully integrate its music service into Google+, it could give the company a seriously needed competitive advantage in taking on Apple. Launched as recently as this summer, the infant social network already has over 40 million registered users as of October, according to CEO Larry Page.

In its first real push into social networking, Apple launched the largely unpopular Ping music service last year. Tied to iTunes, Ping gave users the ability to share and recommend tracks by following one another based on user-created Ping profiles.

But Ping flopped, most likely due to its isolation from the Facebook application programming interface. Integration with the massive social network could have allowed users to search for Facebook friends who have Ping profiles, driving user adoption to Apple’s infant service. Apple tried to make up for it later with Twitter integration, though to no avail.

Both Google and Apple have competition from another major competitor in the social music domain: Facebook. The social media giant recently launched a major overhaul of its user interface and application system at its F8 developer conference in September, pushing deeper into the media sharing domain. The revamp includes partnerships with music services Spotify, Rdio and Mog, with users able to share which tracks they’re listening to with their Facebook friends. It’s everything Ping should have been, but wasn’t.

So the approach for Google, then, is multi-pronged. Integration with its fledgling social network, coupled with the leverage it has in the 200 million activated Android devices available platform-wide, all tied in to its app, which remains free.

The mobile landscape is flooded with Google’s handsets. The challenge is, will customers use them to listen to music? Or will they revert to iTunes?