I've committed a new plugin to Spartacus that allows users to use a very simply Notification System.
Users can create text (HTML formatting configurable) that will appear on the Admin Backend. A small goodie is a feature that notifications are subject to specific usergroups - only the usergroups for which the creator intentionally posted the message will see it.
The plugin also allows to configure whether normal users are allowed to use the messaging system. In the future this could be enhanced for more granular control, but for the time being it should proove a nice tool. The display of the messages can be controlled via a bundled notes.css CSS file.
CSS formatting also allows to format new incoming messages differently. Now try it out and have fun