Update 1.2 is now available in Windows Store and Windows Phone Store. It contains the ability to scrobble tracks to last.fm but this has to be activated separately in the app settings (default setting is Disabled). SonicStreamer will use the last.fm account credentials which are stored in the Subsonic user settings.
I also fixed the playback view for the Windows Phone app. In some cases the page didn’t displayed the correct track. During the tests I observed that SonicStreamer didn’t crashed anymore after the app restart. I hope this issue is also fixed now.