There was two bugs with the multimedia keybindings. They are both fixed with the 2.6.0.3 version of control-center. The corresponding package will be uploaded today. Please, test it.
For reference, see : * http://bugzilla.gnome.org/show_bug.cgi?id=135031 * http://bugzilla.gnome.org/show_bug.cgi?id=138701
