Rdio, the on-demand social music service from the founders of Skype, has opened up its service to developers and published a mobile playback API for iOS, although the current terms of use prohibit the sale of any apps made using it. Instead, the company will make mobile apps work with its affiliate scheme. "We're working on providing a good affiliate program flow for mobile apps so that you can monetize that way. Getting that working well is one of my top priorities so you'll hear about
