Thanks Nick, the Last Published column could show indeed ideally the last published date to a configurable target type, or default to the last publish action to any target. It would make it easier to identify outdated content vs fresh content. Having that date available as a filter in the advanced search would be great too. 

When we load a list of items, we actually obtain the full item data excluding content. This item data includes things like the version and revision, the name and ID of the user to whom the item is currently checked out, and for items in workflow the assignee/performer. We're considering exposing this information by adding a feature to allow users to customize which columns appear in the list. Unfortunately, the individual item data doesn't include last published dates, so this 'configurable columns' feature on its own won't help.

Given that the publish date can be different for each target type, would you expect the 'Last published' column to show the most recent date for a particular (e.g. configurable) target type?

Note that while the publishing information is not available in the list for easy overview/sorting, etc., this information is shown for the selected item in the 'Published to' panel.