spotify-iphone-mobileStreaming music service Spotify is growing rapidly in Europe via its downloadable PC client, but mobile appears to be the next frontier. A series of job ads on the company’s website reveal its plans to launch apps for iPhone, Android and Nokia’s Series 60 platform.The ads, which are all for software engineers, carry a similar wording, promising applicants that “You’ll help us make Spotify mobile”. Besides the different coding experience required for each platform, the ads suggest that applicants will also have “a couple of hobby projects that you want to show us”.What’s unclear is how soon Spotify is aiming to launch apps for these three mobile platforms – whether development is already underway, or if it’ll kick off once these job positions are filled. Meanwhile, a separate job ad for a sales director in France hints that it may be the next country to open up registration for the free version of the service to all – following the UK.