Free online-radio service Pandora may be profitable next year, the first time since its launch 9 years ago, as the number of its subscribers continue to climb, boosted by the release of its mobile application for Apple’s iPhone and RIM’s Blackberry devices, reports Bloomberg. Founder Tim Westergren told the newswire that Pandora, which currently has 27 million registered users, could double its revenues to $40 million this year, as the ad-supported service adds some 50,000 – 60,000 members a day. As much as forty percent of those users are being driven by Pandora’s iPhone app, which currently reigns as the App Store’s most popular music app, ten months after its debut. According to Westergren, the app has more than 5 million users and brings in between 18,000 to 20,000 new users a day. “It’s a whole new world for us,” said Westergren. He added that the app had helped change people’s perceptions of internet radio as something once tied to a PC to something that could now be accessed while on the move.

Pandora plans to earn more revenues off of listeners moving to mobile platforms by increasing the number of audio commercials it plays to two or three 15-second spots an hour up. Users currently may hear only one ad an hour, as well as seeing display ads on the web site and the mobile app. But as Pandora CEO Joe Kennedy said at our recent econSM Conference, “We don’t want you looking at an ad while you’re driving.”

Pandora’s mobile app boost echoes the recent news that music identification service Shazam had doubled its user base from September, as app stores—and again, most notably Apple’s—was driving the increase in users.

• @ EconSM: More Audio Ads Likely Coming To Pandora
• Interview: Andrew Fisher, CEO, Shazam: App Stores Will Give Us 100 Million Users