I'm going to provide coverart via a tag-changed signal pointing to a temp image file containing the cover art, or file icon in general.

About FM radio I want to go the way of a tiny D-Bus service in C++ for controlling the tuner. That way audio doesn't get interrupted when Maemo freezes the application because it will be a daemon in the background.
Then making a FM radio frontent should become an easy task.

But in the next two weeks I will be very very busy and not work on MediaBox much (Google invited me for an on-site job interview in Dublin).