Facebook plans to launch a music platform at its f8 conference in San Francisco on 9/22, a source with knowledge of the plans tells CNBC.

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The social network's music platform launch has been long rumored, but has not yet materialized. The Facebook music launch would be significant because Facebook's huge user base (more than 750 million users) could provide a new marketplace for recording artists and music publishers.

What's less clear is exactly how Facebook's music platform would work. Checks within the music industry suggest that Facebook has not been negotiating to actually become a music retailer itself; instead, it may be creating an environment where third-party music services such as Pandora, Spotify, MOG and others can offer their wares. If that's the case, rather than threaten existing music services, a Facebook music platform could actually provide a boost in traffic to those that offer free, ad-supported services.

A music launch would fit the vision Facebook CEO Mark Zuckerberg outlined earlier this year, when he said it's now best to judge Facebook's growth based on the volume of content users are sharing, rather than on the raw number of active users.

Coming in September, a Facebook music launch would also put Facebook in closer competition with Apple

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[AAPL  Loading...      ()   ], which does its annual music event in September. Apple, the world's largest music retailer, typically updates its iTunes software and updates its line of iPods in September.

Facebook and Apple butted heads after Apple's music event last year, when Apple rolled launched its Ping social network. Ping included Facebook integration, but without Facebook's blessing. Apple removed tight Facebook integration from Ping, and has since partnered more closely with Twitter, a rival social utility.

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