It’s not quite official but there’s little doubt that Google will launch its Google Music service at its big I/O event later today. While the Wall Street Journal couldn’t get a Google spokesman to admit it, Peter Kafka over at All Things D got Jamie Rosenberg, Director of Android Product Management, to spill the details a bit early. Google’s service will essentially mimic the music locker functionality of Amazon’s Cloud service, albeit without the ability to sell songs direct to consumers. Ouch. Unfortunately, Google’s plans to launch a more feature-complete service were derailed when discussions with the labels broke down. According to Rosenberg, “A couple of the major labels were less focused on the innovative vision that we put forward, and more interested in an unreasonable and unsustainable set of business terms.” So, rather than putting the service on hold, Google will launch its music service with the ability to store up to 20,000 of your own uploaded songs for free which you can then stream over the web to your desktop or Android phone or tablet — any device that supports Flash (don’t worry iOS users, your time will come). Amazon’s service, by comparison, offers just 5GB of free storage for about 1,200 songs stored at a mediocre bitrate. Google will also best Amazon with a feature that automatically creates playlists. Google expects to roll out the service to its US users within “weeks” with Music Beta invites going out later today to Verizon Xoom owners (others will be able to sign up at music.google.com). Keep it right here because we’ll be bringing you the announcement live.