This could be done using an Asides plugin, plus Edit N Place plugin. Or the text widget.
But that's a complete waste of resources, because there won't be more posts in the Asides category, just edits. And for the text widget, if I want to edit a typo or whatever, I must go all the way to the widgets section... extremely non productive.
A simple plugin that adds one or more section(s) on the sidebar, that is/are directly editable (AJAX) on the page view for a user that has enough permission to use it.
Widget support, optional.