The service is invitation-only to start. Verizon Xoom owners will receive invitations and others can sign up at music.google.com. Users download an application to their computer and upload their music, which could take many hours. The songs will be available on any device linked to the user’s Google account using a mobile app or a Web-based player, as long as they support Flash, which excludes iPhones and iPads.
Users can store 20,000 songs free, as opposed to Amazon’s service, which stores up to 1,000 songs without charge.