Los Angeles-based music subscription service Napster said Friday that it has launched its Napster Mobile music service on O2 UK, the UK-based wireless carrier. The service, which Napster is co-developing with Ericsson, allows users to subscribe to and purchase music tracks. Ericsson is hosting, integrating, and managing all of the operations of the service for O2 UK. Napster is also in a deal with Ericsson to bring its services to Latin America.