Spotify, the streaming music service which is gradually gathering a large fan-base in Europe, and is poised to launch in the US, has been plotting a mobile version for a while. It recently hired a head of mobile and the speculation was that it would come out with an iPhone app first after releasing a teaser video. But today it’s released video of an Android app it’s being demoing to people at Google I/O.

The Android app is still very much a work in progress and subject to minor changes, but it gives a pretty good overview of their thinking. The demo highlights a number of features including playback, playlists, offline synch and music search.

For those of you who haven’t seen it yet – the service has yet to launch in North America, although I’m about to send some lucky TechCrunch writers some preview codes we’ve gotten hold of – Spotify is a lightweight iTunes-like application for Windows and Mac that lets you search, browse and stream a deep collection of music.