It is relatively simple to create a plugin to do this, but it would just duplicate functionality that exists using search/replace as per that link that dwanthny pointed you at. In a future version of the Quality Check plugin I may incorporate something like that.
There are already a bewildering away of GUI things related to authors - Search and Replace, the Manage Authors dialog, search queries and a tweak. It is a highly confusing and overly complicated part of Calibre imho. A user should be asked in the wizard when they first start Calibre whether they want to display their authors as FN LN or LN, FN, and have a flip author name menu/button for when they have imported it the wrong way around. Maybe I am just wishfully over-simplifying it.