Red hot Stockholm-based music startup Spotify has appointed Gustav Söderström as director of “portable solutions”. This clearly means Spotify intends to exand its music streaming service into the mobile arena. Söderström is a serial entrepreneur, joining Yahoo! in 2006 after his early-player mobile social software company Kenet Works AB was acquired. For the last two years he’s been Director of Product Management and later Director of Business Development in Yahoo! but clearly the startup life has tempted him again. Daniel Ek is CEO of Spotify.

He says on his blog today:

Like many others , my first time using Spotify gave me that very rare ”Wooha!, wait a minute!”-feeling. I got that same feeling using Skype for the first time a few years back. It wasn’t the VoIP technology, I’d used loads of other VoIP apps before, it was the implementation of the service. The fact that it just worked! I didn’t have to care about firewalls, NATs, VoIP servers or user SIP domains (because they didn’t use SIP). And the core proposition of the service, voice, had awesome quality! Even more importantly, because of this, my friends, and even my parents, got it to work!

More tellingly he says:

“Starting in February, I will head up something that a lot of users have already requested and discussed extensively, Spotify on the Mobile.”

This is a key win for Spotify. I interviewed Söderström four years ago for some research into mobile social networking and it was clear then that this was a guy who is technically and strategically very adept. Spotify is getting a lot of great press at the moment and is understood to have raised a massive €15.3m from Northzone Venture Partners.