Overall goal: I'd like to have a Filter Results gadget display issues where the issue has been updated but the logged in user hasn't viewed them.

You can see in the attached picture that both the "Updated" field and the "Last Viewed" fields can be displayed in a Filter Results gadget. However, in the JQL of the Filter you can't use
updatedDate > lastViewed
in the WHERE clause.
We are running JIRA 5.2.