Searching Content Back-end Currently in the admin panel, all entries per channel appear in a single list. Is it at all possible (at least, by default) to filter/search by type?

For instance a dropdown of all entry types, or just 'type: article' in the search form.

I know it is quite easy to do from the front-end, would it require a plugin to add the functionality to the back-end?
Indeed: http://buildwithcraft.com/docs/searching

Anywhere there is a search bar in the control panel, you can use any of the syntaxes listed on that page.