Except for that re-implementation of the registry in Gnome where ´rm .config/sthg´ doesn't work anymore but you have to:

    gsettings reset-recursively org.gnome.rhythmbox
    gsettings reset-recursively org.gnome.rhythmbox.display-page-tree
    gsettings reset-recursively org.gnome.rhythmbox.library
    (...)

http://askubuntu.com/questions/7979/how-can-i-reset-all-rhyt...

(had to do that today to unbork an ipod which rhythmbox wouln't play along anymore)