First of all: The widget issue is not related to the kernel-power! How did you install kernel-power? Pure apt-get or HildonApplicationManager (HAM) or FasterApplicationManager (FAM)? The widget in question seems to be the 'Ovi by Nokia'-widget. You could disable it by: Tapping on an empty space of the desktop, where the infamous widget resides, and dit the cross icon on the upper right corner of the widget. Or you could get rid forever by uninstalling it in FAP from the 'Advanced' category or in X-terminal Code: sudo gainroot apt-get purge ovi-promotion-widget obviously 'rootsh' must be installed for the above commands to work.
sudo gainroot apt-get purge ovi-promotion-widget